diff --git a/debugger/apiv2/controller2_client.go b/debugger/apiv2/controller2_client.go
index 5c07d56..0cc67ab 100644
--- a/debugger/apiv2/controller2_client.go
+++ b/debugger/apiv2/controller2_client.go
@@ -27,6 +27,7 @@
 	clouddebuggerpb "google.golang.org/genproto/googleapis/devtools/clouddebugger/v2"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/metadata"
 )
 
 // Controller2CallOptions contains the retry settings for each method of Controller2Client.
@@ -77,7 +78,7 @@
 	CallOptions *Controller2CallOptions
 
 	// The metadata to be sent with each request.
-	xGoogHeader []string
+	Metadata metadata.MD
 }
 
 // NewController2Client creates a new controller2 client.
@@ -134,7 +135,7 @@
 func (c *Controller2Client) SetGoogleClientInfo(keyval ...string) {
 	kv := append([]string{"gl-go", version.Go()}, keyval...)
 	kv = append(kv, "gapic", version.Repo, "gax", gax.Version, "grpc", grpc.Version)
-	c.xGoogHeader = []string{gax.XGoogHeader(kv...)}
+	c.Metadata = metadata.Pairs("x-goog-api-client", gax.XGoogHeader(kv...))
 }
 
 // RegisterDebuggee registers the debuggee with the controller service.
@@ -148,7 +149,7 @@
 // from data loss, or change the debuggee_id format. Agents must handle
 // debuggee_id value changing upon re-registration.
 func (c *Controller2Client) RegisterDebuggee(ctx context.Context, req *clouddebuggerpb.RegisterDebuggeeRequest, opts ...gax.CallOption) (*clouddebuggerpb.RegisterDebuggeeResponse, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.RegisterDebuggee[0:len(c.CallOptions.RegisterDebuggee):len(c.CallOptions.RegisterDebuggee)], opts...)
 	var resp *clouddebuggerpb.RegisterDebuggeeResponse
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -176,7 +177,7 @@
 // until the controller removes them from the active list to avoid
 // setting those breakpoints again.
 func (c *Controller2Client) ListActiveBreakpoints(ctx context.Context, req *clouddebuggerpb.ListActiveBreakpointsRequest, opts ...gax.CallOption) (*clouddebuggerpb.ListActiveBreakpointsResponse, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.ListActiveBreakpoints[0:len(c.CallOptions.ListActiveBreakpoints):len(c.CallOptions.ListActiveBreakpoints)], opts...)
 	var resp *clouddebuggerpb.ListActiveBreakpointsResponse
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -199,7 +200,7 @@
 // semantics. These may only make changes such as canonicalizing a value
 // or snapping the location to the correct line of code.
 func (c *Controller2Client) UpdateActiveBreakpoint(ctx context.Context, req *clouddebuggerpb.UpdateActiveBreakpointRequest, opts ...gax.CallOption) (*clouddebuggerpb.UpdateActiveBreakpointResponse, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.UpdateActiveBreakpoint[0:len(c.CallOptions.UpdateActiveBreakpoint):len(c.CallOptions.UpdateActiveBreakpoint)], opts...)
 	var resp *clouddebuggerpb.UpdateActiveBreakpointResponse
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
diff --git a/debugger/apiv2/debugger2_client.go b/debugger/apiv2/debugger2_client.go
index a726f1f..bc1181d 100644
--- a/debugger/apiv2/debugger2_client.go
+++ b/debugger/apiv2/debugger2_client.go
@@ -27,6 +27,7 @@
 	clouddebuggerpb "google.golang.org/genproto/googleapis/devtools/clouddebugger/v2"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/metadata"
 )
 
 // Debugger2CallOptions contains the retry settings for each method of Debugger2Client.
@@ -81,7 +82,7 @@
 	CallOptions *Debugger2CallOptions
 
 	// The metadata to be sent with each request.
-	xGoogHeader []string
+	Metadata metadata.MD
 }
 
 // NewDebugger2Client creates a new debugger2 client.
@@ -130,12 +131,12 @@
 func (c *Debugger2Client) SetGoogleClientInfo(keyval ...string) {
 	kv := append([]string{"gl-go", version.Go()}, keyval...)
 	kv = append(kv, "gapic", version.Repo, "gax", gax.Version, "grpc", grpc.Version)
-	c.xGoogHeader = []string{gax.XGoogHeader(kv...)}
+	c.Metadata = metadata.Pairs("x-goog-api-client", gax.XGoogHeader(kv...))
 }
 
 // SetBreakpoint sets the breakpoint to the debuggee.
 func (c *Debugger2Client) SetBreakpoint(ctx context.Context, req *clouddebuggerpb.SetBreakpointRequest, opts ...gax.CallOption) (*clouddebuggerpb.SetBreakpointResponse, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.SetBreakpoint[0:len(c.CallOptions.SetBreakpoint):len(c.CallOptions.SetBreakpoint)], opts...)
 	var resp *clouddebuggerpb.SetBreakpointResponse
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -151,7 +152,7 @@
 
 // GetBreakpoint gets breakpoint information.
 func (c *Debugger2Client) GetBreakpoint(ctx context.Context, req *clouddebuggerpb.GetBreakpointRequest, opts ...gax.CallOption) (*clouddebuggerpb.GetBreakpointResponse, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.GetBreakpoint[0:len(c.CallOptions.GetBreakpoint):len(c.CallOptions.GetBreakpoint)], opts...)
 	var resp *clouddebuggerpb.GetBreakpointResponse
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -167,7 +168,7 @@
 
 // DeleteBreakpoint deletes the breakpoint from the debuggee.
 func (c *Debugger2Client) DeleteBreakpoint(ctx context.Context, req *clouddebuggerpb.DeleteBreakpointRequest, opts ...gax.CallOption) error {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.DeleteBreakpoint[0:len(c.CallOptions.DeleteBreakpoint):len(c.CallOptions.DeleteBreakpoint)], opts...)
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
 		var err error
@@ -179,7 +180,7 @@
 
 // ListBreakpoints lists all breakpoints for the debuggee.
 func (c *Debugger2Client) ListBreakpoints(ctx context.Context, req *clouddebuggerpb.ListBreakpointsRequest, opts ...gax.CallOption) (*clouddebuggerpb.ListBreakpointsResponse, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.ListBreakpoints[0:len(c.CallOptions.ListBreakpoints):len(c.CallOptions.ListBreakpoints)], opts...)
 	var resp *clouddebuggerpb.ListBreakpointsResponse
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -195,7 +196,7 @@
 
 // ListDebuggees lists all the debuggees that the user has access to.
 func (c *Debugger2Client) ListDebuggees(ctx context.Context, req *clouddebuggerpb.ListDebuggeesRequest, opts ...gax.CallOption) (*clouddebuggerpb.ListDebuggeesResponse, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.ListDebuggees[0:len(c.CallOptions.ListDebuggees):len(c.CallOptions.ListDebuggees)], opts...)
 	var resp *clouddebuggerpb.ListDebuggeesResponse
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
diff --git a/debugger/apiv2/doc.go b/debugger/apiv2/doc.go
index 94d9f2b..7a78e85 100644
--- a/debugger/apiv2/doc.go
+++ b/debugger/apiv2/doc.go
@@ -14,9 +14,11 @@
 
 // AUTO-GENERATED CODE. DO NOT EDIT.
 
-// Package debugger is an experimental, auto-generated package for the
+// Package debugger is an auto-generated package for the
 // Stackdriver Debugger API.
 //
+//   NOTE: This package is in alpha. It is not stable, and is likely to be subject to changes.
+//
 // Examines the call stack and variables of a running application
 // without stopping or slowing it down.
 //
@@ -28,11 +30,15 @@
 	"google.golang.org/grpc/metadata"
 )
 
-func insertXGoog(ctx context.Context, val []string) context.Context {
-	md, _ := metadata.FromOutgoingContext(ctx)
-	md = md.Copy()
-	md["x-goog-api-client"] = val
-	return metadata.NewOutgoingContext(ctx, md)
+func insertMetadata(ctx context.Context, mds ...metadata.MD) context.Context {
+	out, _ := metadata.FromOutgoingContext(ctx)
+	out = out.Copy()
+	for _, md := range mds {
+		for k, v := range md {
+			out[k] = append(out[k], v...)
+		}
+	}
+	return metadata.NewOutgoingContext(ctx, out)
 }
 
 // DefaultAuthScopes reports the default set of authentication scopes to use with this package.
diff --git a/dlp/apiv2beta1/dlp_client.go b/dlp/apiv2beta1/dlp_client.go
index 4a6f80b..1cf2064 100644
--- a/dlp/apiv2beta1/dlp_client.go
+++ b/dlp/apiv2beta1/dlp_client.go
@@ -30,10 +30,13 @@
 	dlppb "google.golang.org/genproto/googleapis/privacy/dlp/v2beta1"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/metadata"
 )
 
 // CallOptions contains the retry settings for each method of Client.
 type CallOptions struct {
+	DeidentifyContent      []gax.CallOption
+	AnalyzeDataSourceRisk  []gax.CallOption
 	InspectContent         []gax.CallOption
 	RedactContent          []gax.CallOption
 	CreateInspectOperation []gax.CallOption
@@ -65,6 +68,8 @@
 		},
 	}
 	return &CallOptions{
+		DeidentifyContent:      retry[[2]string{"default", "idempotent"}],
+		AnalyzeDataSourceRisk:  retry[[2]string{"default", "idempotent"}],
 		InspectContent:         retry[[2]string{"default", "non_idempotent"}],
 		RedactContent:          retry[[2]string{"default", "non_idempotent"}],
 		CreateInspectOperation: retry[[2]string{"default", "non_idempotent"}],
@@ -91,7 +96,7 @@
 	CallOptions *CallOptions
 
 	// The metadata to be sent with each request.
-	xGoogHeader []string
+	Metadata metadata.MD
 }
 
 // NewClient creates a new dlp service client.
@@ -145,7 +150,7 @@
 func (c *Client) setGoogleClientInfo(keyval ...string) {
 	kv := append([]string{"gl-go", version.Go()}, keyval...)
 	kv = append(kv, "gapic", version.Repo, "gax", gax.Version, "grpc", grpc.Version)
-	c.xGoogHeader = []string{gax.XGoogHeader(kv...)}
+	c.Metadata = metadata.Pairs("x-goog-api-client", gax.XGoogHeader(kv...))
 }
 
 // ResultPath returns the path for the result resource.
@@ -156,10 +161,46 @@
 		""
 }
 
+// DeidentifyContent de-identifies potentially sensitive info from a list of strings.
+// This method has limits on input size and output size.
+func (c *Client) DeidentifyContent(ctx context.Context, req *dlppb.DeidentifyContentRequest, opts ...gax.CallOption) (*dlppb.DeidentifyContentResponse, error) {
+	ctx = insertMetadata(ctx, c.Metadata)
+	opts = append(c.CallOptions.DeidentifyContent[0:len(c.CallOptions.DeidentifyContent):len(c.CallOptions.DeidentifyContent)], opts...)
+	var resp *dlppb.DeidentifyContentResponse
+	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
+		var err error
+		resp, err = c.client.DeidentifyContent(ctx, req, settings.GRPC...)
+		return err
+	}, opts...)
+	if err != nil {
+		return nil, err
+	}
+	return resp, nil
+}
+
+// AnalyzeDataSourceRisk schedules a job to compute risk analysis metrics over content in a Google
+// Cloud Platform repository.
+func (c *Client) AnalyzeDataSourceRisk(ctx context.Context, req *dlppb.AnalyzeDataSourceRiskRequest, opts ...gax.CallOption) (*AnalyzeDataSourceRiskOperation, error) {
+	ctx = insertMetadata(ctx, c.Metadata)
+	opts = append(c.CallOptions.AnalyzeDataSourceRisk[0:len(c.CallOptions.AnalyzeDataSourceRisk):len(c.CallOptions.AnalyzeDataSourceRisk)], opts...)
+	var resp *longrunningpb.Operation
+	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
+		var err error
+		resp, err = c.client.AnalyzeDataSourceRisk(ctx, req, settings.GRPC...)
+		return err
+	}, opts...)
+	if err != nil {
+		return nil, err
+	}
+	return &AnalyzeDataSourceRiskOperation{
+		lro: longrunning.InternalNewOperation(c.LROClient, resp),
+	}, nil
+}
+
 // InspectContent finds potentially sensitive info in a list of strings.
 // This method has limits on input size, processing time, and output size.
 func (c *Client) InspectContent(ctx context.Context, req *dlppb.InspectContentRequest, opts ...gax.CallOption) (*dlppb.InspectContentResponse, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.InspectContent[0:len(c.CallOptions.InspectContent):len(c.CallOptions.InspectContent)], opts...)
 	var resp *dlppb.InspectContentResponse
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -176,7 +217,7 @@
 // RedactContent redacts potentially sensitive info from a list of strings.
 // This method has limits on input size, processing time, and output size.
 func (c *Client) RedactContent(ctx context.Context, req *dlppb.RedactContentRequest, opts ...gax.CallOption) (*dlppb.RedactContentResponse, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.RedactContent[0:len(c.CallOptions.RedactContent):len(c.CallOptions.RedactContent)], opts...)
 	var resp *dlppb.RedactContentResponse
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -193,7 +234,7 @@
 // CreateInspectOperation schedules a job scanning content in a Google Cloud Platform data
 // repository.
 func (c *Client) CreateInspectOperation(ctx context.Context, req *dlppb.CreateInspectOperationRequest, opts ...gax.CallOption) (*CreateInspectOperationHandle, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.CreateInspectOperation[0:len(c.CallOptions.CreateInspectOperation):len(c.CallOptions.CreateInspectOperation)], opts...)
 	var resp *longrunningpb.Operation
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -211,7 +252,7 @@
 
 // ListInspectFindings returns list of results for given inspect operation result set id.
 func (c *Client) ListInspectFindings(ctx context.Context, req *dlppb.ListInspectFindingsRequest, opts ...gax.CallOption) (*dlppb.ListInspectFindingsResponse, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.ListInspectFindings[0:len(c.CallOptions.ListInspectFindings):len(c.CallOptions.ListInspectFindings)], opts...)
 	var resp *dlppb.ListInspectFindingsResponse
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -227,7 +268,7 @@
 
 // ListInfoTypes returns sensitive information types for given category.
 func (c *Client) ListInfoTypes(ctx context.Context, req *dlppb.ListInfoTypesRequest, opts ...gax.CallOption) (*dlppb.ListInfoTypesResponse, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.ListInfoTypes[0:len(c.CallOptions.ListInfoTypes):len(c.CallOptions.ListInfoTypes)], opts...)
 	var resp *dlppb.ListInfoTypesResponse
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -243,7 +284,7 @@
 
 // ListRootCategories returns the list of root categories of sensitive information.
 func (c *Client) ListRootCategories(ctx context.Context, req *dlppb.ListRootCategoriesRequest, opts ...gax.CallOption) (*dlppb.ListRootCategoriesResponse, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.ListRootCategories[0:len(c.CallOptions.ListRootCategories):len(c.CallOptions.ListRootCategories)], opts...)
 	var resp *dlppb.ListRootCategoriesResponse
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -257,6 +298,75 @@
 	return resp, nil
 }
 
+// AnalyzeDataSourceRiskOperation manages a long-running operation from AnalyzeDataSourceRisk.
+type AnalyzeDataSourceRiskOperation struct {
+	lro *longrunning.Operation
+}
+
+// AnalyzeDataSourceRiskOperation returns a new AnalyzeDataSourceRiskOperation from a given name.
+// The name must be that of a previously created AnalyzeDataSourceRiskOperation, possibly from a different process.
+func (c *Client) AnalyzeDataSourceRiskOperation(name string) *AnalyzeDataSourceRiskOperation {
+	return &AnalyzeDataSourceRiskOperation{
+		lro: longrunning.InternalNewOperation(c.LROClient, &longrunningpb.Operation{Name: name}),
+	}
+}
+
+// Wait blocks until the long-running operation is completed, returning the response and any errors encountered.
+//
+// See documentation of Poll for error-handling information.
+func (op *AnalyzeDataSourceRiskOperation) Wait(ctx context.Context, opts ...gax.CallOption) (*dlppb.RiskAnalysisOperationResult, error) {
+	var resp dlppb.RiskAnalysisOperationResult
+	if err := op.lro.WaitWithInterval(ctx, &resp, 45000*time.Millisecond, opts...); err != nil {
+		return nil, err
+	}
+	return &resp, nil
+}
+
+// Poll fetches the latest state of the long-running operation.
+//
+// Poll also fetches the latest metadata, which can be retrieved by Metadata.
+//
+// If Poll fails, the error is returned and op is unmodified. If Poll succeeds and
+// the operation has completed with failure, the error is returned and op.Done will return true.
+// If Poll succeeds and the operation has completed successfully,
+// op.Done will return true, and the response of the operation is returned.
+// If Poll succeeds and the operation has not completed, the returned response and error are both nil.
+func (op *AnalyzeDataSourceRiskOperation) Poll(ctx context.Context, opts ...gax.CallOption) (*dlppb.RiskAnalysisOperationResult, error) {
+	var resp dlppb.RiskAnalysisOperationResult
+	if err := op.lro.Poll(ctx, &resp, opts...); err != nil {
+		return nil, err
+	}
+	if !op.Done() {
+		return nil, nil
+	}
+	return &resp, nil
+}
+
+// Metadata returns metadata associated with the long-running operation.
+// Metadata itself does not contact the server, but Poll does.
+// To get the latest metadata, call this method after a successful call to Poll.
+// If the metadata is not available, the returned metadata and error are both nil.
+func (op *AnalyzeDataSourceRiskOperation) Metadata() (*dlppb.RiskAnalysisOperationMetadata, error) {
+	var meta dlppb.RiskAnalysisOperationMetadata
+	if err := op.lro.Metadata(&meta); err == longrunning.ErrNoMetadata {
+		return nil, nil
+	} else if err != nil {
+		return nil, err
+	}
+	return &meta, nil
+}
+
+// Done reports whether the long-running operation has completed.
+func (op *AnalyzeDataSourceRiskOperation) Done() bool {
+	return op.lro.Done()
+}
+
+// Name returns the name of the long-running operation.
+// The name is assigned by the server and is unique within the service from which the operation is created.
+func (op *AnalyzeDataSourceRiskOperation) Name() string {
+	return op.lro.Name()
+}
+
 // CreateInspectOperationHandle manages a long-running operation from CreateInspectOperation.
 type CreateInspectOperationHandle struct {
 	lro *longrunning.Operation
diff --git a/dlp/apiv2beta1/dlp_client_example_test.go b/dlp/apiv2beta1/dlp_client_example_test.go
index 714ae5b..86398c1 100644
--- a/dlp/apiv2beta1/dlp_client_example_test.go
+++ b/dlp/apiv2beta1/dlp_client_example_test.go
@@ -32,6 +32,47 @@
 	_ = c
 }
 
+func ExampleClient_DeidentifyContent() {
+	ctx := context.Background()
+	c, err := dlp.NewClient(ctx)
+	if err != nil {
+		// TODO: Handle error.
+	}
+
+	req := &dlppb.DeidentifyContentRequest{
+	// TODO: Fill request struct fields.
+	}
+	resp, err := c.DeidentifyContent(ctx, req)
+	if err != nil {
+		// TODO: Handle error.
+	}
+	// TODO: Use resp.
+	_ = resp
+}
+
+func ExampleClient_AnalyzeDataSourceRisk() {
+	ctx := context.Background()
+	c, err := dlp.NewClient(ctx)
+	if err != nil {
+		// TODO: Handle error.
+	}
+
+	req := &dlppb.AnalyzeDataSourceRiskRequest{
+	// TODO: Fill request struct fields.
+	}
+	op, err := c.AnalyzeDataSourceRisk(ctx, req)
+	if err != nil {
+		// TODO: Handle error.
+	}
+
+	resp, err := op.Wait(ctx)
+	if err != nil {
+		// TODO: Handle error.
+	}
+	// TODO: Use resp.
+	_ = resp
+}
+
 func ExampleClient_InspectContent() {
 	ctx := context.Background()
 	c, err := dlp.NewClient(ctx)
diff --git a/dlp/apiv2beta1/doc.go b/dlp/apiv2beta1/doc.go
index af6e0d9..cfd8d65 100644
--- a/dlp/apiv2beta1/doc.go
+++ b/dlp/apiv2beta1/doc.go
@@ -14,9 +14,11 @@
 
 // AUTO-GENERATED CODE. DO NOT EDIT.
 
-// Package dlp is an experimental, auto-generated package for the
+// Package dlp is an auto-generated package for the
 // DLP API.
 //
+//   NOTE: This package is in alpha. It is not stable, and is likely to be subject to changes.
+//
 // The Google Data Loss Prevention API provides methods for detection of
 // privacy-sensitive fragments in text, images, and Google Cloud Platform
 // storage repositories.
@@ -27,11 +29,15 @@
 	"google.golang.org/grpc/metadata"
 )
 
-func insertXGoog(ctx context.Context, val []string) context.Context {
-	md, _ := metadata.FromOutgoingContext(ctx)
-	md = md.Copy()
-	md["x-goog-api-client"] = val
-	return metadata.NewOutgoingContext(ctx, md)
+func insertMetadata(ctx context.Context, mds ...metadata.MD) context.Context {
+	out, _ := metadata.FromOutgoingContext(ctx)
+	out = out.Copy()
+	for _, md := range mds {
+		for k, v := range md {
+			out[k] = append(out[k], v...)
+		}
+	}
+	return metadata.NewOutgoingContext(ctx, out)
 }
 
 // DefaultAuthScopes reports the default set of authentication scopes to use with this package.
diff --git a/dlp/apiv2beta1/mock_test.go b/dlp/apiv2beta1/mock_test.go
index 45d4c4f..1fe5ae2 100644
--- a/dlp/apiv2beta1/mock_test.go
+++ b/dlp/apiv2beta1/mock_test.go
@@ -85,6 +85,18 @@
 	return s.resps[0].(*dlppb.RedactContentResponse), nil
 }
 
+func (s *mockDlpServer) DeidentifyContent(ctx context.Context, req *dlppb.DeidentifyContentRequest) (*dlppb.DeidentifyContentResponse, error) {
+	md, _ := metadata.FromIncomingContext(ctx)
+	if xg := md["x-goog-api-client"]; len(xg) == 0 || !strings.Contains(xg[0], "gl-go/") {
+		return nil, fmt.Errorf("x-goog-api-client = %v, expected gl-go key", xg)
+	}
+	s.reqs = append(s.reqs, req)
+	if s.err != nil {
+		return nil, s.err
+	}
+	return s.resps[0].(*dlppb.DeidentifyContentResponse), nil
+}
+
 func (s *mockDlpServer) CreateInspectOperation(ctx context.Context, req *dlppb.CreateInspectOperationRequest) (*longrunningpb.Operation, error) {
 	md, _ := metadata.FromIncomingContext(ctx)
 	if xg := md["x-goog-api-client"]; len(xg) == 0 || !strings.Contains(xg[0], "gl-go/") {
@@ -97,6 +109,18 @@
 	return s.resps[0].(*longrunningpb.Operation), nil
 }
 
+func (s *mockDlpServer) AnalyzeDataSourceRisk(ctx context.Context, req *dlppb.AnalyzeDataSourceRiskRequest) (*longrunningpb.Operation, error) {
+	md, _ := metadata.FromIncomingContext(ctx)
+	if xg := md["x-goog-api-client"]; len(xg) == 0 || !strings.Contains(xg[0], "gl-go/") {
+		return nil, fmt.Errorf("x-goog-api-client = %v, expected gl-go key", xg)
+	}
+	s.reqs = append(s.reqs, req)
+	if s.err != nil {
+		return nil, s.err
+	}
+	return s.resps[0].(*longrunningpb.Operation), nil
+}
+
 func (s *mockDlpServer) ListInspectFindings(ctx context.Context, req *dlppb.ListInspectFindingsRequest) (*dlppb.ListInspectFindingsResponse, error) {
 	md, _ := metadata.FromIncomingContext(ctx)
 	if xg := md["x-goog-api-client"]; len(xg) == 0 || !strings.Contains(xg[0], "gl-go/") {
@@ -162,6 +186,156 @@
 	os.Exit(m.Run())
 }
 
+func TestDlpServiceDeidentifyContent(t *testing.T) {
+	var expectedResponse *dlppb.DeidentifyContentResponse = &dlppb.DeidentifyContentResponse{}
+
+	mockDlp.err = nil
+	mockDlp.reqs = nil
+
+	mockDlp.resps = append(mockDlp.resps[:0], expectedResponse)
+
+	var deidentifyConfig *dlppb.DeidentifyConfig = &dlppb.DeidentifyConfig{}
+	var inspectConfig *dlppb.InspectConfig = &dlppb.InspectConfig{}
+	var items []*dlppb.ContentItem = nil
+	var request = &dlppb.DeidentifyContentRequest{
+		DeidentifyConfig: deidentifyConfig,
+		InspectConfig:    inspectConfig,
+		Items:            items,
+	}
+
+	c, err := NewClient(context.Background(), clientOpt)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	resp, err := c.DeidentifyContent(context.Background(), request)
+
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if want, got := request, mockDlp.reqs[0]; !proto.Equal(want, got) {
+		t.Errorf("wrong request %q, want %q", got, want)
+	}
+
+	if want, got := expectedResponse, resp; !proto.Equal(want, got) {
+		t.Errorf("wrong response %q, want %q)", got, want)
+	}
+}
+
+func TestDlpServiceDeidentifyContentError(t *testing.T) {
+	errCode := codes.PermissionDenied
+	mockDlp.err = gstatus.Error(errCode, "test error")
+
+	var deidentifyConfig *dlppb.DeidentifyConfig = &dlppb.DeidentifyConfig{}
+	var inspectConfig *dlppb.InspectConfig = &dlppb.InspectConfig{}
+	var items []*dlppb.ContentItem = nil
+	var request = &dlppb.DeidentifyContentRequest{
+		DeidentifyConfig: deidentifyConfig,
+		InspectConfig:    inspectConfig,
+		Items:            items,
+	}
+
+	c, err := NewClient(context.Background(), clientOpt)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	resp, err := c.DeidentifyContent(context.Background(), request)
+
+	if st, ok := gstatus.FromError(err); !ok {
+		t.Errorf("got error %v, expected grpc error", err)
+	} else if c := st.Code(); c != errCode {
+		t.Errorf("got error code %q, want %q", c, errCode)
+	}
+	_ = resp
+}
+func TestDlpServiceAnalyzeDataSourceRisk(t *testing.T) {
+	var expectedResponse *dlppb.RiskAnalysisOperationResult = &dlppb.RiskAnalysisOperationResult{}
+
+	mockDlp.err = nil
+	mockDlp.reqs = nil
+
+	any, err := ptypes.MarshalAny(expectedResponse)
+	if err != nil {
+		t.Fatal(err)
+	}
+	mockDlp.resps = append(mockDlp.resps[:0], &longrunningpb.Operation{
+		Name:   "longrunning-test",
+		Done:   true,
+		Result: &longrunningpb.Operation_Response{Response: any},
+	})
+
+	var privacyMetric *dlppb.PrivacyMetric = &dlppb.PrivacyMetric{}
+	var sourceTable *dlppb.BigQueryTable = &dlppb.BigQueryTable{}
+	var request = &dlppb.AnalyzeDataSourceRiskRequest{
+		PrivacyMetric: privacyMetric,
+		SourceTable:   sourceTable,
+	}
+
+	c, err := NewClient(context.Background(), clientOpt)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	respLRO, err := c.AnalyzeDataSourceRisk(context.Background(), request)
+	if err != nil {
+		t.Fatal(err)
+	}
+	resp, err := respLRO.Wait(context.Background())
+
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if want, got := request, mockDlp.reqs[0]; !proto.Equal(want, got) {
+		t.Errorf("wrong request %q, want %q", got, want)
+	}
+
+	if want, got := expectedResponse, resp; !proto.Equal(want, got) {
+		t.Errorf("wrong response %q, want %q)", got, want)
+	}
+}
+
+func TestDlpServiceAnalyzeDataSourceRiskError(t *testing.T) {
+	errCode := codes.PermissionDenied
+	mockDlp.err = nil
+	mockDlp.resps = append(mockDlp.resps[:0], &longrunningpb.Operation{
+		Name: "longrunning-test",
+		Done: true,
+		Result: &longrunningpb.Operation_Error{
+			Error: &status.Status{
+				Code:    int32(errCode),
+				Message: "test error",
+			},
+		},
+	})
+
+	var privacyMetric *dlppb.PrivacyMetric = &dlppb.PrivacyMetric{}
+	var sourceTable *dlppb.BigQueryTable = &dlppb.BigQueryTable{}
+	var request = &dlppb.AnalyzeDataSourceRiskRequest{
+		PrivacyMetric: privacyMetric,
+		SourceTable:   sourceTable,
+	}
+
+	c, err := NewClient(context.Background(), clientOpt)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	respLRO, err := c.AnalyzeDataSourceRisk(context.Background(), request)
+	if err != nil {
+		t.Fatal(err)
+	}
+	resp, err := respLRO.Wait(context.Background())
+
+	if st, ok := gstatus.FromError(err); !ok {
+		t.Errorf("got error %v, expected grpc error", err)
+	} else if c := st.Code(); c != errCode {
+		t.Errorf("got error code %q, want %q", c, errCode)
+	}
+	_ = resp
+}
 func TestDlpServiceInspectContent(t *testing.T) {
 	var expectedResponse *dlppb.InspectContentResponse = &dlppb.InspectContentResponse{}
 
@@ -170,8 +344,23 @@
 
 	mockDlp.resps = append(mockDlp.resps[:0], expectedResponse)
 
-	var inspectConfig *dlppb.InspectConfig = &dlppb.InspectConfig{}
-	var items []*dlppb.ContentItem = nil
+	var name string = "EMAIL_ADDRESS"
+	var infoTypesElement = &dlppb.InfoType{
+		Name: name,
+	}
+	var infoTypes = []*dlppb.InfoType{infoTypesElement}
+	var inspectConfig = &dlppb.InspectConfig{
+		InfoTypes: infoTypes,
+	}
+	var type_ string = "text/plain"
+	var value string = "My email is example@example.com."
+	var itemsElement = &dlppb.ContentItem{
+		Type: type_,
+		DataItem: &dlppb.ContentItem_Value{
+			Value: value,
+		},
+	}
+	var items = []*dlppb.ContentItem{itemsElement}
 	var request = &dlppb.InspectContentRequest{
 		InspectConfig: inspectConfig,
 		Items:         items,
@@ -201,8 +390,23 @@
 	errCode := codes.PermissionDenied
 	mockDlp.err = gstatus.Error(errCode, "test error")
 
-	var inspectConfig *dlppb.InspectConfig = &dlppb.InspectConfig{}
-	var items []*dlppb.ContentItem = nil
+	var name string = "EMAIL_ADDRESS"
+	var infoTypesElement = &dlppb.InfoType{
+		Name: name,
+	}
+	var infoTypes = []*dlppb.InfoType{infoTypesElement}
+	var inspectConfig = &dlppb.InspectConfig{
+		InfoTypes: infoTypes,
+	}
+	var type_ string = "text/plain"
+	var value string = "My email is example@example.com."
+	var itemsElement = &dlppb.ContentItem{
+		Type: type_,
+		DataItem: &dlppb.ContentItem_Value{
+			Value: value,
+		},
+	}
+	var items = []*dlppb.ContentItem{itemsElement}
 	var request = &dlppb.InspectContentRequest{
 		InspectConfig: inspectConfig,
 		Items:         items,
@@ -230,9 +434,33 @@
 
 	mockDlp.resps = append(mockDlp.resps[:0], expectedResponse)
 
-	var inspectConfig *dlppb.InspectConfig = &dlppb.InspectConfig{}
-	var items []*dlppb.ContentItem = nil
-	var replaceConfigs []*dlppb.RedactContentRequest_ReplaceConfig = nil
+	var name string = "EMAIL_ADDRESS"
+	var infoTypesElement = &dlppb.InfoType{
+		Name: name,
+	}
+	var infoTypes = []*dlppb.InfoType{infoTypesElement}
+	var inspectConfig = &dlppb.InspectConfig{
+		InfoTypes: infoTypes,
+	}
+	var type_ string = "text/plain"
+	var value string = "My email is example@example.com."
+	var itemsElement = &dlppb.ContentItem{
+		Type: type_,
+		DataItem: &dlppb.ContentItem_Value{
+			Value: value,
+		},
+	}
+	var items = []*dlppb.ContentItem{itemsElement}
+	var name2 string = "EMAIL_ADDRESS"
+	var infoType = &dlppb.InfoType{
+		Name: name2,
+	}
+	var replaceWith string = "REDACTED"
+	var replaceConfigsElement = &dlppb.RedactContentRequest_ReplaceConfig{
+		InfoType:    infoType,
+		ReplaceWith: replaceWith,
+	}
+	var replaceConfigs = []*dlppb.RedactContentRequest_ReplaceConfig{replaceConfigsElement}
 	var request = &dlppb.RedactContentRequest{
 		InspectConfig:  inspectConfig,
 		Items:          items,
@@ -263,9 +491,33 @@
 	errCode := codes.PermissionDenied
 	mockDlp.err = gstatus.Error(errCode, "test error")
 
-	var inspectConfig *dlppb.InspectConfig = &dlppb.InspectConfig{}
-	var items []*dlppb.ContentItem = nil
-	var replaceConfigs []*dlppb.RedactContentRequest_ReplaceConfig = nil
+	var name string = "EMAIL_ADDRESS"
+	var infoTypesElement = &dlppb.InfoType{
+		Name: name,
+	}
+	var infoTypes = []*dlppb.InfoType{infoTypesElement}
+	var inspectConfig = &dlppb.InspectConfig{
+		InfoTypes: infoTypes,
+	}
+	var type_ string = "text/plain"
+	var value string = "My email is example@example.com."
+	var itemsElement = &dlppb.ContentItem{
+		Type: type_,
+		DataItem: &dlppb.ContentItem_Value{
+			Value: value,
+		},
+	}
+	var items = []*dlppb.ContentItem{itemsElement}
+	var name2 string = "EMAIL_ADDRESS"
+	var infoType = &dlppb.InfoType{
+		Name: name2,
+	}
+	var replaceWith string = "REDACTED"
+	var replaceConfigsElement = &dlppb.RedactContentRequest_ReplaceConfig{
+		InfoType:    infoType,
+		ReplaceWith: replaceWith,
+	}
+	var replaceConfigs = []*dlppb.RedactContentRequest_ReplaceConfig{replaceConfigsElement}
 	var request = &dlppb.RedactContentRequest{
 		InspectConfig:  inspectConfig,
 		Items:          items,
@@ -287,9 +539,9 @@
 	_ = resp
 }
 func TestDlpServiceCreateInspectOperation(t *testing.T) {
-	var name string = "name3373707"
+	var name2 string = "name2-1052831874"
 	var expectedResponse = &dlppb.InspectOperationResult{
-		Name: name,
+		Name: name2,
 	}
 
 	mockDlp.err = nil
@@ -305,8 +557,26 @@
 		Result: &longrunningpb.Operation_Response{Response: any},
 	})
 
-	var inspectConfig *dlppb.InspectConfig = &dlppb.InspectConfig{}
-	var storageConfig *dlppb.StorageConfig = &dlppb.StorageConfig{}
+	var name string = "EMAIL_ADDRESS"
+	var infoTypesElement = &dlppb.InfoType{
+		Name: name,
+	}
+	var infoTypes = []*dlppb.InfoType{infoTypesElement}
+	var inspectConfig = &dlppb.InspectConfig{
+		InfoTypes: infoTypes,
+	}
+	var url string = "gs://example_bucket/example_file.png"
+	var fileSet = &dlppb.CloudStorageOptions_FileSet{
+		Url: url,
+	}
+	var cloudStorageOptions = &dlppb.CloudStorageOptions{
+		FileSet: fileSet,
+	}
+	var storageConfig = &dlppb.StorageConfig{
+		Type: &dlppb.StorageConfig_CloudStorageOptions{
+			CloudStorageOptions: cloudStorageOptions,
+		},
+	}
 	var outputConfig *dlppb.OutputStorageConfig = &dlppb.OutputStorageConfig{}
 	var request = &dlppb.CreateInspectOperationRequest{
 		InspectConfig: inspectConfig,
@@ -352,8 +622,26 @@
 		},
 	})
 
-	var inspectConfig *dlppb.InspectConfig = &dlppb.InspectConfig{}
-	var storageConfig *dlppb.StorageConfig = &dlppb.StorageConfig{}
+	var name string = "EMAIL_ADDRESS"
+	var infoTypesElement = &dlppb.InfoType{
+		Name: name,
+	}
+	var infoTypes = []*dlppb.InfoType{infoTypesElement}
+	var inspectConfig = &dlppb.InspectConfig{
+		InfoTypes: infoTypes,
+	}
+	var url string = "gs://example_bucket/example_file.png"
+	var fileSet = &dlppb.CloudStorageOptions_FileSet{
+		Url: url,
+	}
+	var cloudStorageOptions = &dlppb.CloudStorageOptions{
+		FileSet: fileSet,
+	}
+	var storageConfig = &dlppb.StorageConfig{
+		Type: &dlppb.StorageConfig_CloudStorageOptions{
+			CloudStorageOptions: cloudStorageOptions,
+		},
+	}
 	var outputConfig *dlppb.OutputStorageConfig = &dlppb.OutputStorageConfig{}
 	var request = &dlppb.CreateInspectOperationRequest{
 		InspectConfig: inspectConfig,
@@ -446,8 +734,8 @@
 
 	mockDlp.resps = append(mockDlp.resps[:0], expectedResponse)
 
-	var category string = "category50511102"
-	var languageCode string = "languageCode-412800396"
+	var category string = "PII"
+	var languageCode string = "en"
 	var request = &dlppb.ListInfoTypesRequest{
 		Category:     category,
 		LanguageCode: languageCode,
@@ -477,8 +765,8 @@
 	errCode := codes.PermissionDenied
 	mockDlp.err = gstatus.Error(errCode, "test error")
 
-	var category string = "category50511102"
-	var languageCode string = "languageCode-412800396"
+	var category string = "PII"
+	var languageCode string = "en"
 	var request = &dlppb.ListInfoTypesRequest{
 		Category:     category,
 		LanguageCode: languageCode,
@@ -506,7 +794,7 @@
 
 	mockDlp.resps = append(mockDlp.resps[:0], expectedResponse)
 
-	var languageCode string = "languageCode-412800396"
+	var languageCode string = "en"
 	var request = &dlppb.ListRootCategoriesRequest{
 		LanguageCode: languageCode,
 	}
@@ -535,7 +823,7 @@
 	errCode := codes.PermissionDenied
 	mockDlp.err = gstatus.Error(errCode, "test error")
 
-	var languageCode string = "languageCode-412800396"
+	var languageCode string = "en"
 	var request = &dlppb.ListRootCategoriesRequest{
 		LanguageCode: languageCode,
 	}
diff --git a/errorreporting/apiv1beta1/doc.go b/errorreporting/apiv1beta1/doc.go
index 5f94124..43ee1b9 100644
--- a/errorreporting/apiv1beta1/doc.go
+++ b/errorreporting/apiv1beta1/doc.go
@@ -14,9 +14,11 @@
 
 // AUTO-GENERATED CODE. DO NOT EDIT.
 
-// Package errorreporting is an experimental, auto-generated package for the
+// Package errorreporting is an auto-generated package for the
 // Stackdriver Error Reporting API.
 //
+//   NOTE: This package is in alpha. It is not stable, and is likely to be subject to changes.
+//
 // Stackdriver Error Reporting groups and counts similar errors from cloud
 // services. The Stackdriver Error Reporting API provides a way to report new
 // errors and read access to error groups and their associated errors.
@@ -29,11 +31,15 @@
 	"google.golang.org/grpc/metadata"
 )
 
-func insertXGoog(ctx context.Context, val []string) context.Context {
-	md, _ := metadata.FromOutgoingContext(ctx)
-	md = md.Copy()
-	md["x-goog-api-client"] = val
-	return metadata.NewOutgoingContext(ctx, md)
+func insertMetadata(ctx context.Context, mds ...metadata.MD) context.Context {
+	out, _ := metadata.FromOutgoingContext(ctx)
+	out = out.Copy()
+	for _, md := range mds {
+		for k, v := range md {
+			out[k] = append(out[k], v...)
+		}
+	}
+	return metadata.NewOutgoingContext(ctx, out)
 }
 
 // DefaultAuthScopes reports the default set of authentication scopes to use with this package.
diff --git a/errorreporting/apiv1beta1/error_group_client.go b/errorreporting/apiv1beta1/error_group_client.go
index f2d2194..919b1e9 100644
--- a/errorreporting/apiv1beta1/error_group_client.go
+++ b/errorreporting/apiv1beta1/error_group_client.go
@@ -27,6 +27,7 @@
 	clouderrorreportingpb "google.golang.org/genproto/googleapis/devtools/clouderrorreporting/v1beta1"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/metadata"
 )
 
 // ErrorGroupCallOptions contains the retry settings for each method of ErrorGroupClient.
@@ -75,7 +76,7 @@
 	CallOptions *ErrorGroupCallOptions
 
 	// The metadata to be sent with each request.
-	xGoogHeader []string
+	Metadata metadata.MD
 }
 
 // NewErrorGroupClient creates a new error group service client.
@@ -113,7 +114,7 @@
 func (c *ErrorGroupClient) SetGoogleClientInfo(keyval ...string) {
 	kv := append([]string{"gl-go", version.Go()}, keyval...)
 	kv = append(kv, "gapic", version.Repo, "gax", gax.Version, "grpc", grpc.Version)
-	c.xGoogHeader = []string{gax.XGoogHeader(kv...)}
+	c.Metadata = metadata.Pairs("x-goog-api-client", gax.XGoogHeader(kv...))
 }
 
 // ErrorGroupGroupPath returns the path for the group resource.
@@ -128,7 +129,7 @@
 
 // GetGroup get the specified group.
 func (c *ErrorGroupClient) GetGroup(ctx context.Context, req *clouderrorreportingpb.GetGroupRequest, opts ...gax.CallOption) (*clouderrorreportingpb.ErrorGroup, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.GetGroup[0:len(c.CallOptions.GetGroup):len(c.CallOptions.GetGroup)], opts...)
 	var resp *clouderrorreportingpb.ErrorGroup
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -145,7 +146,7 @@
 // UpdateGroup replace the data for the specified group.
 // Fails if the group does not exist.
 func (c *ErrorGroupClient) UpdateGroup(ctx context.Context, req *clouderrorreportingpb.UpdateGroupRequest, opts ...gax.CallOption) (*clouderrorreportingpb.ErrorGroup, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.UpdateGroup[0:len(c.CallOptions.UpdateGroup):len(c.CallOptions.UpdateGroup)], opts...)
 	var resp *clouderrorreportingpb.ErrorGroup
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
diff --git a/errorreporting/apiv1beta1/error_stats_client.go b/errorreporting/apiv1beta1/error_stats_client.go
index e9150a0..a7c86bc 100644
--- a/errorreporting/apiv1beta1/error_stats_client.go
+++ b/errorreporting/apiv1beta1/error_stats_client.go
@@ -29,6 +29,7 @@
 	clouderrorreportingpb "google.golang.org/genproto/googleapis/devtools/clouderrorreporting/v1beta1"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/metadata"
 )
 
 // ErrorStatsCallOptions contains the retry settings for each method of ErrorStatsClient.
@@ -79,7 +80,7 @@
 	CallOptions *ErrorStatsCallOptions
 
 	// The metadata to be sent with each request.
-	xGoogHeader []string
+	Metadata metadata.MD
 }
 
 // NewErrorStatsClient creates a new error stats service client.
@@ -118,7 +119,7 @@
 func (c *ErrorStatsClient) SetGoogleClientInfo(keyval ...string) {
 	kv := append([]string{"gl-go", version.Go()}, keyval...)
 	kv = append(kv, "gapic", version.Repo, "gax", gax.Version, "grpc", grpc.Version)
-	c.xGoogHeader = []string{gax.XGoogHeader(kv...)}
+	c.Metadata = metadata.Pairs("x-goog-api-client", gax.XGoogHeader(kv...))
 }
 
 // ErrorStatsProjectPath returns the path for the project resource.
@@ -131,7 +132,7 @@
 
 // ListGroupStats lists the specified groups.
 func (c *ErrorStatsClient) ListGroupStats(ctx context.Context, req *clouderrorreportingpb.ListGroupStatsRequest, opts ...gax.CallOption) *ErrorGroupStatsIterator {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.ListGroupStats[0:len(c.CallOptions.ListGroupStats):len(c.CallOptions.ListGroupStats)], opts...)
 	it := &ErrorGroupStatsIterator{}
 	it.InternalFetch = func(pageSize int, pageToken string) ([]*clouderrorreportingpb.ErrorGroupStats, string, error) {
@@ -166,7 +167,7 @@
 
 // ListEvents lists the specified events.
 func (c *ErrorStatsClient) ListEvents(ctx context.Context, req *clouderrorreportingpb.ListEventsRequest, opts ...gax.CallOption) *ErrorEventIterator {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.ListEvents[0:len(c.CallOptions.ListEvents):len(c.CallOptions.ListEvents)], opts...)
 	it := &ErrorEventIterator{}
 	it.InternalFetch = func(pageSize int, pageToken string) ([]*clouderrorreportingpb.ErrorEvent, string, error) {
@@ -201,7 +202,7 @@
 
 // DeleteEvents deletes all error events of a given project.
 func (c *ErrorStatsClient) DeleteEvents(ctx context.Context, req *clouderrorreportingpb.DeleteEventsRequest, opts ...gax.CallOption) (*clouderrorreportingpb.DeleteEventsResponse, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.DeleteEvents[0:len(c.CallOptions.DeleteEvents):len(c.CallOptions.DeleteEvents)], opts...)
 	var resp *clouderrorreportingpb.DeleteEventsResponse
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
diff --git a/errorreporting/apiv1beta1/report_errors_client.go b/errorreporting/apiv1beta1/report_errors_client.go
index bf8f98c..1a5510c 100644
--- a/errorreporting/apiv1beta1/report_errors_client.go
+++ b/errorreporting/apiv1beta1/report_errors_client.go
@@ -24,6 +24,7 @@
 	"google.golang.org/api/transport"
 	clouderrorreportingpb "google.golang.org/genproto/googleapis/devtools/clouderrorreporting/v1beta1"
 	"google.golang.org/grpc"
+	"google.golang.org/grpc/metadata"
 )
 
 // ReportErrorsCallOptions contains the retry settings for each method of ReportErrorsClient.
@@ -57,7 +58,7 @@
 	CallOptions *ReportErrorsCallOptions
 
 	// The metadata to be sent with each request.
-	xGoogHeader []string
+	Metadata metadata.MD
 }
 
 // NewReportErrorsClient creates a new report errors service client.
@@ -95,7 +96,7 @@
 func (c *ReportErrorsClient) SetGoogleClientInfo(keyval ...string) {
 	kv := append([]string{"gl-go", version.Go()}, keyval...)
 	kv = append(kv, "gapic", version.Repo, "gax", gax.Version, "grpc", grpc.Version)
-	c.xGoogHeader = []string{gax.XGoogHeader(kv...)}
+	c.Metadata = metadata.Pairs("x-goog-api-client", gax.XGoogHeader(kv...))
 }
 
 // ReportErrorsProjectPath returns the path for the project resource.
@@ -114,7 +115,7 @@
 // for authentication. To use an API key, append it to the URL as the value of
 // a key parameter. For example:<pre>POST https://clouderrorreporting.googleapis.com/v1beta1/projects/example-project/events:report?key=123ABC456</pre>
 func (c *ReportErrorsClient) ReportErrorEvent(ctx context.Context, req *clouderrorreportingpb.ReportErrorEventRequest, opts ...gax.CallOption) (*clouderrorreportingpb.ReportErrorEventResponse, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.ReportErrorEvent[0:len(c.CallOptions.ReportErrorEvent):len(c.CallOptions.ReportErrorEvent)], opts...)
 	var resp *clouderrorreportingpb.ReportErrorEventResponse
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
diff --git a/firestore/apiv1beta1/doc.go b/firestore/apiv1beta1/doc.go
index ef585cf..a5b5c1c 100644
--- a/firestore/apiv1beta1/doc.go
+++ b/firestore/apiv1beta1/doc.go
@@ -21,18 +21,22 @@
 //
 //
 // Use the client at cloud.google.com/go/firestore in preference to this.
-package firestore
+package firestore // import "cloud.google.com/go/firestore/apiv1beta1"
 
 import (
 	"golang.org/x/net/context"
 	"google.golang.org/grpc/metadata"
 )
 
-func insertXGoog(ctx context.Context, val []string) context.Context {
-	md, _ := metadata.FromOutgoingContext(ctx)
-	md = md.Copy()
-	md["x-goog-api-client"] = val
-	return metadata.NewOutgoingContext(ctx, md)
+func insertMetadata(ctx context.Context, mds ...metadata.MD) context.Context {
+	out, _ := metadata.FromOutgoingContext(ctx)
+	out = out.Copy()
+	for _, md := range mds {
+		for k, v := range md {
+			out[k] = append(out[k], v...)
+		}
+	}
+	return metadata.NewOutgoingContext(ctx, out)
 }
 
 // DefaultAuthScopes reports the default set of authentication scopes to use with this package.
diff --git a/firestore/apiv1beta1/firestore_client.go b/firestore/apiv1beta1/firestore_client.go
index b536156..862641d 100644
--- a/firestore/apiv1beta1/firestore_client.go
+++ b/firestore/apiv1beta1/firestore_client.go
@@ -21,15 +21,15 @@
 	"time"
 
 	"cloud.google.com/go/internal/version"
-	firestorepb "google.golang.org/genproto/googleapis/firestore/v1beta1"
-
 	gax "github.com/googleapis/gax-go"
 	"golang.org/x/net/context"
 	"google.golang.org/api/iterator"
 	"google.golang.org/api/option"
 	"google.golang.org/api/transport"
+	firestorepb "google.golang.org/genproto/googleapis/firestore/v1beta1"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/metadata"
 )
 
 // CallOptions contains the retry settings for each method of Client.
@@ -112,7 +112,7 @@
 	CallOptions *CallOptions
 
 	// The metadata to be sent with each request.
-	xGoogHeader []string
+	Metadata metadata.MD
 }
 
 // NewClient creates a new firestore client.
@@ -168,7 +168,7 @@
 func (c *Client) SetGoogleClientInfo(keyval ...string) {
 	kv := append([]string{"gl-go", version.Go()}, keyval...)
 	kv = append(kv, "gapic", version.Repo, "gax", gax.Version, "grpc", grpc.Version)
-	c.xGoogHeader = []string{gax.XGoogHeader(kv...)}
+	c.Metadata = metadata.Pairs("x-goog-api-client", gax.XGoogHeader(kv...))
 }
 
 // DatabaseRootPath returns the path for the database root resource.
@@ -220,7 +220,7 @@
 
 // GetDocument gets a single document.
 func (c *Client) GetDocument(ctx context.Context, req *firestorepb.GetDocumentRequest, opts ...gax.CallOption) (*firestorepb.Document, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.GetDocument[0:len(c.CallOptions.GetDocument):len(c.CallOptions.GetDocument)], opts...)
 	var resp *firestorepb.Document
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -236,7 +236,7 @@
 
 // ListDocuments lists documents.
 func (c *Client) ListDocuments(ctx context.Context, req *firestorepb.ListDocumentsRequest, opts ...gax.CallOption) *DocumentIterator {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.ListDocuments[0:len(c.CallOptions.ListDocuments):len(c.CallOptions.ListDocuments)], opts...)
 	it := &DocumentIterator{}
 	it.InternalFetch = func(pageSize int, pageToken string) ([]*firestorepb.Document, string, error) {
@@ -271,7 +271,7 @@
 
 // CreateDocument creates a new document.
 func (c *Client) CreateDocument(ctx context.Context, req *firestorepb.CreateDocumentRequest, opts ...gax.CallOption) (*firestorepb.Document, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.CreateDocument[0:len(c.CallOptions.CreateDocument):len(c.CallOptions.CreateDocument)], opts...)
 	var resp *firestorepb.Document
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -287,7 +287,7 @@
 
 // UpdateDocument updates or inserts a document.
 func (c *Client) UpdateDocument(ctx context.Context, req *firestorepb.UpdateDocumentRequest, opts ...gax.CallOption) (*firestorepb.Document, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.UpdateDocument[0:len(c.CallOptions.UpdateDocument):len(c.CallOptions.UpdateDocument)], opts...)
 	var resp *firestorepb.Document
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -303,7 +303,7 @@
 
 // DeleteDocument deletes a document.
 func (c *Client) DeleteDocument(ctx context.Context, req *firestorepb.DeleteDocumentRequest, opts ...gax.CallOption) error {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.DeleteDocument[0:len(c.CallOptions.DeleteDocument):len(c.CallOptions.DeleteDocument)], opts...)
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
 		var err error
@@ -318,7 +318,7 @@
 // Documents returned by this method are not guaranteed to be returned in the
 // same order that they were requested.
 func (c *Client) BatchGetDocuments(ctx context.Context, req *firestorepb.BatchGetDocumentsRequest, opts ...gax.CallOption) (firestorepb.Firestore_BatchGetDocumentsClient, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.BatchGetDocuments[0:len(c.CallOptions.BatchGetDocuments):len(c.CallOptions.BatchGetDocuments)], opts...)
 	var resp firestorepb.Firestore_BatchGetDocumentsClient
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -334,7 +334,7 @@
 
 // BeginTransaction starts a new transaction.
 func (c *Client) BeginTransaction(ctx context.Context, req *firestorepb.BeginTransactionRequest, opts ...gax.CallOption) (*firestorepb.BeginTransactionResponse, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.BeginTransaction[0:len(c.CallOptions.BeginTransaction):len(c.CallOptions.BeginTransaction)], opts...)
 	var resp *firestorepb.BeginTransactionResponse
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -350,7 +350,7 @@
 
 // Commit commits a transaction, while optionally updating documents.
 func (c *Client) Commit(ctx context.Context, req *firestorepb.CommitRequest, opts ...gax.CallOption) (*firestorepb.CommitResponse, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.Commit[0:len(c.CallOptions.Commit):len(c.CallOptions.Commit)], opts...)
 	var resp *firestorepb.CommitResponse
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -366,7 +366,7 @@
 
 // Rollback rolls back a transaction.
 func (c *Client) Rollback(ctx context.Context, req *firestorepb.RollbackRequest, opts ...gax.CallOption) error {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.Rollback[0:len(c.CallOptions.Rollback):len(c.CallOptions.Rollback)], opts...)
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
 		var err error
@@ -378,7 +378,7 @@
 
 // RunQuery runs a query.
 func (c *Client) RunQuery(ctx context.Context, req *firestorepb.RunQueryRequest, opts ...gax.CallOption) (firestorepb.Firestore_RunQueryClient, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.RunQuery[0:len(c.CallOptions.RunQuery):len(c.CallOptions.RunQuery)], opts...)
 	var resp firestorepb.Firestore_RunQueryClient
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -394,7 +394,7 @@
 
 // Write streams batches of document updates and deletes, in order.
 func (c *Client) Write(ctx context.Context, opts ...gax.CallOption) (firestorepb.Firestore_WriteClient, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.Write[0:len(c.CallOptions.Write):len(c.CallOptions.Write)], opts...)
 	var resp firestorepb.Firestore_WriteClient
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -410,7 +410,7 @@
 
 // Listen listens to changes.
 func (c *Client) Listen(ctx context.Context, opts ...gax.CallOption) (firestorepb.Firestore_ListenClient, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.Listen[0:len(c.CallOptions.Listen):len(c.CallOptions.Listen)], opts...)
 	var resp firestorepb.Firestore_ListenClient
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -426,7 +426,7 @@
 
 // ListCollectionIds lists all the collection IDs underneath a document.
 func (c *Client) ListCollectionIds(ctx context.Context, req *firestorepb.ListCollectionIdsRequest, opts ...gax.CallOption) *StringIterator {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.ListCollectionIds[0:len(c.CallOptions.ListCollectionIds):len(c.CallOptions.ListCollectionIds)], opts...)
 	it := &StringIterator{}
 	it.InternalFetch = func(pageSize int, pageToken string) ([]string, string, error) {
diff --git a/firestore/apiv1beta1/firestore_client_example_test.go b/firestore/apiv1beta1/firestore_client_example_test.go
index 4038db2..a0ce89a 100644
--- a/firestore/apiv1beta1/firestore_client_example_test.go
+++ b/firestore/apiv1beta1/firestore_client_example_test.go
@@ -19,11 +19,10 @@
 import (
 	"io"
 
-	firestore "cloud.google.com/go/firestore/apiv1beta1"
-	firestorepb "google.golang.org/genproto/googleapis/firestore/v1beta1"
-
+	"cloud.google.com/go/firestore/apiv1beta1"
 	"golang.org/x/net/context"
 	"google.golang.org/api/iterator"
+	firestorepb "google.golang.org/genproto/googleapis/firestore/v1beta1"
 )
 
 func ExampleNewClient() {
diff --git a/firestore/apiv1beta1/mock_test.go b/firestore/apiv1beta1/mock_test.go
index 9db3a49..fc93a22 100644
--- a/firestore/apiv1beta1/mock_test.go
+++ b/firestore/apiv1beta1/mock_test.go
@@ -17,9 +17,8 @@
 package firestore
 
 import (
-	firestorepb "google.golang.org/genproto/googleapis/firestore/v1beta1"
-
 	emptypb "github.com/golang/protobuf/ptypes/empty"
+	firestorepb "google.golang.org/genproto/googleapis/firestore/v1beta1"
 )
 
 import (
diff --git a/language/apiv1beta2/doc.go b/language/apiv1beta2/doc.go
index 42dc1e5..4899db3 100644
--- a/language/apiv1beta2/doc.go
+++ b/language/apiv1beta2/doc.go
@@ -14,9 +14,11 @@
 
 // AUTO-GENERATED CODE. DO NOT EDIT.
 
-// Package language is an experimental, auto-generated package for the
+// Package language is an auto-generated package for the
 // Google Cloud Natural Language API.
 //
+//   NOTE: This package is in alpha. It is not stable, and is likely to be subject to changes.
+//
 // Google Cloud Natural Language API provides natural language understanding
 // technologies to developers. Examples include sentiment analysis, entity
 // recognition, and text annotations.
@@ -27,11 +29,15 @@
 	"google.golang.org/grpc/metadata"
 )
 
-func insertXGoog(ctx context.Context, val []string) context.Context {
-	md, _ := metadata.FromOutgoingContext(ctx)
-	md = md.Copy()
-	md["x-goog-api-client"] = val
-	return metadata.NewOutgoingContext(ctx, md)
+func insertMetadata(ctx context.Context, mds ...metadata.MD) context.Context {
+	out, _ := metadata.FromOutgoingContext(ctx)
+	out = out.Copy()
+	for _, md := range mds {
+		for k, v := range md {
+			out[k] = append(out[k], v...)
+		}
+	}
+	return metadata.NewOutgoingContext(ctx, out)
 }
 
 // DefaultAuthScopes reports the default set of authentication scopes to use with this package.
diff --git a/language/apiv1beta2/language_client.go b/language/apiv1beta2/language_client.go
index ab541ff..f63c8c8 100644
--- a/language/apiv1beta2/language_client.go
+++ b/language/apiv1beta2/language_client.go
@@ -27,6 +27,7 @@
 	languagepb "google.golang.org/genproto/googleapis/cloud/language/v1beta2"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/metadata"
 )
 
 // CallOptions contains the retry settings for each method of Client.
@@ -83,7 +84,7 @@
 	CallOptions *CallOptions
 
 	// The metadata to be sent with each request.
-	xGoogHeader []string
+	Metadata metadata.MD
 }
 
 // NewClient creates a new language service client.
@@ -122,12 +123,12 @@
 func (c *Client) setGoogleClientInfo(keyval ...string) {
 	kv := append([]string{"gl-go", version.Go()}, keyval...)
 	kv = append(kv, "gapic", version.Repo, "gax", gax.Version, "grpc", grpc.Version)
-	c.xGoogHeader = []string{gax.XGoogHeader(kv...)}
+	c.Metadata = metadata.Pairs("x-goog-api-client", gax.XGoogHeader(kv...))
 }
 
 // AnalyzeSentiment analyzes the sentiment of the provided text.
 func (c *Client) AnalyzeSentiment(ctx context.Context, req *languagepb.AnalyzeSentimentRequest, opts ...gax.CallOption) (*languagepb.AnalyzeSentimentResponse, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.AnalyzeSentiment[0:len(c.CallOptions.AnalyzeSentiment):len(c.CallOptions.AnalyzeSentiment)], opts...)
 	var resp *languagepb.AnalyzeSentimentResponse
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -145,7 +146,7 @@
 // along with entity types, salience, mentions for each entity, and
 // other properties.
 func (c *Client) AnalyzeEntities(ctx context.Context, req *languagepb.AnalyzeEntitiesRequest, opts ...gax.CallOption) (*languagepb.AnalyzeEntitiesResponse, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.AnalyzeEntities[0:len(c.CallOptions.AnalyzeEntities):len(c.CallOptions.AnalyzeEntities)], opts...)
 	var resp *languagepb.AnalyzeEntitiesResponse
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -162,7 +163,7 @@
 // AnalyzeEntitySentiment finds entities, similar to [AnalyzeEntities][google.cloud.language.v1beta2.LanguageService.AnalyzeEntities] in the text and analyzes
 // sentiment associated with each entity and its mentions.
 func (c *Client) AnalyzeEntitySentiment(ctx context.Context, req *languagepb.AnalyzeEntitySentimentRequest, opts ...gax.CallOption) (*languagepb.AnalyzeEntitySentimentResponse, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.AnalyzeEntitySentiment[0:len(c.CallOptions.AnalyzeEntitySentiment):len(c.CallOptions.AnalyzeEntitySentiment)], opts...)
 	var resp *languagepb.AnalyzeEntitySentimentResponse
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -180,7 +181,7 @@
 // tokenization along with part of speech tags, dependency trees, and other
 // properties.
 func (c *Client) AnalyzeSyntax(ctx context.Context, req *languagepb.AnalyzeSyntaxRequest, opts ...gax.CallOption) (*languagepb.AnalyzeSyntaxResponse, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.AnalyzeSyntax[0:len(c.CallOptions.AnalyzeSyntax):len(c.CallOptions.AnalyzeSyntax)], opts...)
 	var resp *languagepb.AnalyzeSyntaxResponse
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -196,7 +197,7 @@
 
 // ClassifyText classifies a document into categories.
 func (c *Client) ClassifyText(ctx context.Context, req *languagepb.ClassifyTextRequest, opts ...gax.CallOption) (*languagepb.ClassifyTextResponse, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.ClassifyText[0:len(c.CallOptions.ClassifyText):len(c.CallOptions.ClassifyText)], opts...)
 	var resp *languagepb.ClassifyTextResponse
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -213,7 +214,7 @@
 // AnnotateText a convenience method that provides all syntax, sentiment, entity, and
 // classification features in one call.
 func (c *Client) AnnotateText(ctx context.Context, req *languagepb.AnnotateTextRequest, opts ...gax.CallOption) (*languagepb.AnnotateTextResponse, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.AnnotateText[0:len(c.CallOptions.AnnotateText):len(c.CallOptions.AnnotateText)], opts...)
 	var resp *languagepb.AnnotateTextResponse
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
diff --git a/logging/apiv2/config_client.go b/logging/apiv2/config_client.go
index 3df8653..99857a1 100644
--- a/logging/apiv2/config_client.go
+++ b/logging/apiv2/config_client.go
@@ -29,15 +29,21 @@
 	loggingpb "google.golang.org/genproto/googleapis/logging/v2"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/metadata"
 )
 
 // ConfigCallOptions contains the retry settings for each method of ConfigClient.
 type ConfigCallOptions struct {
-	ListSinks  []gax.CallOption
-	GetSink    []gax.CallOption
-	CreateSink []gax.CallOption
-	UpdateSink []gax.CallOption
-	DeleteSink []gax.CallOption
+	ListSinks       []gax.CallOption
+	GetSink         []gax.CallOption
+	CreateSink      []gax.CallOption
+	UpdateSink      []gax.CallOption
+	DeleteSink      []gax.CallOption
+	ListExclusions  []gax.CallOption
+	GetExclusion    []gax.CallOption
+	CreateExclusion []gax.CallOption
+	UpdateExclusion []gax.CallOption
+	DeleteExclusion []gax.CallOption
 }
 
 func defaultConfigClientOptions() []option.ClientOption {
@@ -64,11 +70,16 @@
 		},
 	}
 	return &ConfigCallOptions{
-		ListSinks:  retry[[2]string{"default", "idempotent"}],
-		GetSink:    retry[[2]string{"default", "idempotent"}],
-		CreateSink: retry[[2]string{"default", "non_idempotent"}],
-		UpdateSink: retry[[2]string{"default", "non_idempotent"}],
-		DeleteSink: retry[[2]string{"default", "idempotent"}],
+		ListSinks:       retry[[2]string{"default", "idempotent"}],
+		GetSink:         retry[[2]string{"default", "idempotent"}],
+		CreateSink:      retry[[2]string{"default", "non_idempotent"}],
+		UpdateSink:      retry[[2]string{"default", "non_idempotent"}],
+		DeleteSink:      retry[[2]string{"default", "idempotent"}],
+		ListExclusions:  retry[[2]string{"default", "idempotent"}],
+		GetExclusion:    retry[[2]string{"default", "idempotent"}],
+		CreateExclusion: retry[[2]string{"default", "non_idempotent"}],
+		UpdateExclusion: retry[[2]string{"default", "non_idempotent"}],
+		DeleteExclusion: retry[[2]string{"default", "idempotent"}],
 	}
 }
 
@@ -84,7 +95,7 @@
 	CallOptions *ConfigCallOptions
 
 	// The metadata to be sent with each request.
-	xGoogHeader []string
+	Metadata metadata.MD
 }
 
 // NewConfigClient creates a new config service v2 client.
@@ -123,7 +134,7 @@
 func (c *ConfigClient) SetGoogleClientInfo(keyval ...string) {
 	kv := append([]string{"gl-go", version.Go()}, keyval...)
 	kv = append(kv, "gapic", version.Repo, "gax", gax.Version, "grpc", grpc.Version)
-	c.xGoogHeader = []string{gax.XGoogHeader(kv...)}
+	c.Metadata = metadata.Pairs("x-goog-api-client", gax.XGoogHeader(kv...))
 }
 
 // ConfigProjectPath returns the path for the project resource.
@@ -144,9 +155,19 @@
 		""
 }
 
+// ConfigExclusionPath returns the path for the exclusion resource.
+func ConfigExclusionPath(project, exclusion string) string {
+	return "" +
+		"projects/" +
+		project +
+		"/exclusions/" +
+		exclusion +
+		""
+}
+
 // ListSinks lists sinks.
 func (c *ConfigClient) ListSinks(ctx context.Context, req *loggingpb.ListSinksRequest, opts ...gax.CallOption) *LogSinkIterator {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.ListSinks[0:len(c.CallOptions.ListSinks):len(c.CallOptions.ListSinks)], opts...)
 	it := &LogSinkIterator{}
 	it.InternalFetch = func(pageSize int, pageToken string) ([]*loggingpb.LogSink, string, error) {
@@ -181,7 +202,7 @@
 
 // GetSink gets a sink.
 func (c *ConfigClient) GetSink(ctx context.Context, req *loggingpb.GetSinkRequest, opts ...gax.CallOption) (*loggingpb.LogSink, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.GetSink[0:len(c.CallOptions.GetSink):len(c.CallOptions.GetSink)], opts...)
 	var resp *loggingpb.LogSink
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -201,7 +222,7 @@
 // writer_identity is not permitted to write to the destination.  A sink can
 // export log entries only from the resource owning the sink.
 func (c *ConfigClient) CreateSink(ctx context.Context, req *loggingpb.CreateSinkRequest, opts ...gax.CallOption) (*loggingpb.LogSink, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.CreateSink[0:len(c.CallOptions.CreateSink):len(c.CallOptions.CreateSink)], opts...)
 	var resp *loggingpb.LogSink
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -215,16 +236,13 @@
 	return resp, nil
 }
 
-// UpdateSink updates a sink. If the named sink doesn't exist, then this method is
-// identical to
-// sinks.create (at /logging/docs/api/reference/rest/v2/projects.sinks/create).
-// If the named sink does exist, then this method replaces the following
-// fields in the existing sink with values from the new sink: destination,
-// filter, output_version_format, start_time, and end_time.
-// The updated filter might also have a new writer_identity; see the
+// UpdateSink updates a sink.  This method replaces the following fields in the existing
+// sink with values from the new sink: destination, filter,
+// output_version_format, start_time, and end_time.
+// The updated sink might also have a new writer_identity; see the
 // unique_writer_identity field.
 func (c *ConfigClient) UpdateSink(ctx context.Context, req *loggingpb.UpdateSinkRequest, opts ...gax.CallOption) (*loggingpb.LogSink, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.UpdateSink[0:len(c.CallOptions.UpdateSink):len(c.CallOptions.UpdateSink)], opts...)
 	var resp *loggingpb.LogSink
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -241,7 +259,7 @@
 // DeleteSink deletes a sink. If the sink has a unique writer_identity, then that
 // service account is also deleted.
 func (c *ConfigClient) DeleteSink(ctx context.Context, req *loggingpb.DeleteSinkRequest, opts ...gax.CallOption) error {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.DeleteSink[0:len(c.CallOptions.DeleteSink):len(c.CallOptions.DeleteSink)], opts...)
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
 		var err error
@@ -251,6 +269,145 @@
 	return err
 }
 
+// ListExclusions lists all the exclusions in a parent resource.
+func (c *ConfigClient) ListExclusions(ctx context.Context, req *loggingpb.ListExclusionsRequest, opts ...gax.CallOption) *LogExclusionIterator {
+	ctx = insertMetadata(ctx, c.Metadata)
+	opts = append(c.CallOptions.ListExclusions[0:len(c.CallOptions.ListExclusions):len(c.CallOptions.ListExclusions)], opts...)
+	it := &LogExclusionIterator{}
+	it.InternalFetch = func(pageSize int, pageToken string) ([]*loggingpb.LogExclusion, string, error) {
+		var resp *loggingpb.ListExclusionsResponse
+		req.PageToken = pageToken
+		if pageSize > math.MaxInt32 {
+			req.PageSize = math.MaxInt32
+		} else {
+			req.PageSize = int32(pageSize)
+		}
+		err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
+			var err error
+			resp, err = c.configClient.ListExclusions(ctx, req, settings.GRPC...)
+			return err
+		}, opts...)
+		if err != nil {
+			return nil, "", err
+		}
+		return resp.Exclusions, resp.NextPageToken, nil
+	}
+	fetch := func(pageSize int, pageToken string) (string, error) {
+		items, nextPageToken, err := it.InternalFetch(pageSize, pageToken)
+		if err != nil {
+			return "", err
+		}
+		it.items = append(it.items, items...)
+		return nextPageToken, nil
+	}
+	it.pageInfo, it.nextFunc = iterator.NewPageInfo(fetch, it.bufLen, it.takeBuf)
+	return it
+}
+
+// GetExclusion gets the description of an exclusion.
+func (c *ConfigClient) GetExclusion(ctx context.Context, req *loggingpb.GetExclusionRequest, opts ...gax.CallOption) (*loggingpb.LogExclusion, error) {
+	ctx = insertMetadata(ctx, c.Metadata)
+	opts = append(c.CallOptions.GetExclusion[0:len(c.CallOptions.GetExclusion):len(c.CallOptions.GetExclusion)], opts...)
+	var resp *loggingpb.LogExclusion
+	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
+		var err error
+		resp, err = c.configClient.GetExclusion(ctx, req, settings.GRPC...)
+		return err
+	}, opts...)
+	if err != nil {
+		return nil, err
+	}
+	return resp, nil
+}
+
+// CreateExclusion creates a new exclusion in a specified parent resource.
+// Only log entries belonging to that resource can be excluded.
+// You can have up to 10 exclusions in a resource.
+func (c *ConfigClient) CreateExclusion(ctx context.Context, req *loggingpb.CreateExclusionRequest, opts ...gax.CallOption) (*loggingpb.LogExclusion, error) {
+	ctx = insertMetadata(ctx, c.Metadata)
+	opts = append(c.CallOptions.CreateExclusion[0:len(c.CallOptions.CreateExclusion):len(c.CallOptions.CreateExclusion)], opts...)
+	var resp *loggingpb.LogExclusion
+	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
+		var err error
+		resp, err = c.configClient.CreateExclusion(ctx, req, settings.GRPC...)
+		return err
+	}, opts...)
+	if err != nil {
+		return nil, err
+	}
+	return resp, nil
+}
+
+// UpdateExclusion changes one or more properties of an existing exclusion.
+func (c *ConfigClient) UpdateExclusion(ctx context.Context, req *loggingpb.UpdateExclusionRequest, opts ...gax.CallOption) (*loggingpb.LogExclusion, error) {
+	ctx = insertMetadata(ctx, c.Metadata)
+	opts = append(c.CallOptions.UpdateExclusion[0:len(c.CallOptions.UpdateExclusion):len(c.CallOptions.UpdateExclusion)], opts...)
+	var resp *loggingpb.LogExclusion
+	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
+		var err error
+		resp, err = c.configClient.UpdateExclusion(ctx, req, settings.GRPC...)
+		return err
+	}, opts...)
+	if err != nil {
+		return nil, err
+	}
+	return resp, nil
+}
+
+// DeleteExclusion deletes an exclusion.
+func (c *ConfigClient) DeleteExclusion(ctx context.Context, req *loggingpb.DeleteExclusionRequest, opts ...gax.CallOption) error {
+	ctx = insertMetadata(ctx, c.Metadata)
+	opts = append(c.CallOptions.DeleteExclusion[0:len(c.CallOptions.DeleteExclusion):len(c.CallOptions.DeleteExclusion)], opts...)
+	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
+		var err error
+		_, err = c.configClient.DeleteExclusion(ctx, req, settings.GRPC...)
+		return err
+	}, opts...)
+	return err
+}
+
+// LogExclusionIterator manages a stream of *loggingpb.LogExclusion.
+type LogExclusionIterator struct {
+	items    []*loggingpb.LogExclusion
+	pageInfo *iterator.PageInfo
+	nextFunc func() error
+
+	// InternalFetch is for use by the Google Cloud Libraries only.
+	// It is not part of the stable interface of this package.
+	//
+	// InternalFetch returns results from a single call to the underlying RPC.
+	// The number of results is no greater than pageSize.
+	// If there are no more results, nextPageToken is empty and err is nil.
+	InternalFetch func(pageSize int, pageToken string) (results []*loggingpb.LogExclusion, nextPageToken string, err error)
+}
+
+// PageInfo supports pagination. See the google.golang.org/api/iterator package for details.
+func (it *LogExclusionIterator) PageInfo() *iterator.PageInfo {
+	return it.pageInfo
+}
+
+// Next returns the next result. Its second return value is iterator.Done if there are no more
+// results. Once Next returns Done, all subsequent calls will return Done.
+func (it *LogExclusionIterator) Next() (*loggingpb.LogExclusion, error) {
+	var item *loggingpb.LogExclusion
+	if err := it.nextFunc(); err != nil {
+		return item, err
+	}
+	item = it.items[0]
+	it.items = it.items[1:]
+	return item, nil
+}
+
+func (it *LogExclusionIterator) bufLen() int {
+	return len(it.items)
+}
+
+func (it *LogExclusionIterator) takeBuf() interface{} {
+	b := it.items
+	it.items = nil
+	return b
+}
+
 // LogSinkIterator manages a stream of *loggingpb.LogSink.
 type LogSinkIterator struct {
 	items    []*loggingpb.LogSink
diff --git a/logging/apiv2/config_client_example_test.go b/logging/apiv2/config_client_example_test.go
index 7369260..92726aa 100644
--- a/logging/apiv2/config_client_example_test.go
+++ b/logging/apiv2/config_client_example_test.go
@@ -126,3 +126,97 @@
 		// TODO: Handle error.
 	}
 }
+
+func ExampleConfigClient_ListExclusions() {
+	ctx := context.Background()
+	c, err := logging.NewConfigClient(ctx)
+	if err != nil {
+		// TODO: Handle error.
+	}
+
+	req := &loggingpb.ListExclusionsRequest{
+	// TODO: Fill request struct fields.
+	}
+	it := c.ListExclusions(ctx, req)
+	for {
+		resp, err := it.Next()
+		if err == iterator.Done {
+			break
+		}
+		if err != nil {
+			// TODO: Handle error.
+		}
+		// TODO: Use resp.
+		_ = resp
+	}
+}
+
+func ExampleConfigClient_GetExclusion() {
+	ctx := context.Background()
+	c, err := logging.NewConfigClient(ctx)
+	if err != nil {
+		// TODO: Handle error.
+	}
+
+	req := &loggingpb.GetExclusionRequest{
+	// TODO: Fill request struct fields.
+	}
+	resp, err := c.GetExclusion(ctx, req)
+	if err != nil {
+		// TODO: Handle error.
+	}
+	// TODO: Use resp.
+	_ = resp
+}
+
+func ExampleConfigClient_CreateExclusion() {
+	ctx := context.Background()
+	c, err := logging.NewConfigClient(ctx)
+	if err != nil {
+		// TODO: Handle error.
+	}
+
+	req := &loggingpb.CreateExclusionRequest{
+	// TODO: Fill request struct fields.
+	}
+	resp, err := c.CreateExclusion(ctx, req)
+	if err != nil {
+		// TODO: Handle error.
+	}
+	// TODO: Use resp.
+	_ = resp
+}
+
+func ExampleConfigClient_UpdateExclusion() {
+	ctx := context.Background()
+	c, err := logging.NewConfigClient(ctx)
+	if err != nil {
+		// TODO: Handle error.
+	}
+
+	req := &loggingpb.UpdateExclusionRequest{
+	// TODO: Fill request struct fields.
+	}
+	resp, err := c.UpdateExclusion(ctx, req)
+	if err != nil {
+		// TODO: Handle error.
+	}
+	// TODO: Use resp.
+	_ = resp
+}
+
+func ExampleConfigClient_DeleteExclusion() {
+	ctx := context.Background()
+	c, err := logging.NewConfigClient(ctx)
+	if err != nil {
+		// TODO: Handle error.
+	}
+
+	req := &loggingpb.DeleteExclusionRequest{
+	// TODO: Fill request struct fields.
+	}
+	err = c.DeleteExclusion(ctx, req)
+	if err != nil {
+		// TODO: Handle error.
+	}
+}
diff --git a/logging/apiv2/doc.go b/logging/apiv2/doc.go
index 77c43c7..1fd4991 100644
--- a/logging/apiv2/doc.go
+++ b/logging/apiv2/doc.go
@@ -14,9 +14,11 @@
 
 // AUTO-GENERATED CODE. DO NOT EDIT.
 
-// Package logging is an experimental, auto-generated package for the
+// Package logging is an auto-generated package for the
 // Stackdriver Logging API.
 //
+//   NOTE: This package is in alpha. It is not stable, and is likely to be subject to changes.
+//
 // The Stackdriver Logging API lets you write log entries and manage your
 // logs, log sinks and logs-based metrics.
 //
@@ -28,11 +30,15 @@
 	"google.golang.org/grpc/metadata"
 )
 
-func insertXGoog(ctx context.Context, val []string) context.Context {
-	md, _ := metadata.FromOutgoingContext(ctx)
-	md = md.Copy()
-	md["x-goog-api-client"] = val
-	return metadata.NewOutgoingContext(ctx, md)
+func insertMetadata(ctx context.Context, mds ...metadata.MD) context.Context {
+	out, _ := metadata.FromOutgoingContext(ctx)
+	out = out.Copy()
+	for _, md := range mds {
+		for k, v := range md {
+			out[k] = append(out[k], v...)
+		}
+	}
+	return metadata.NewOutgoingContext(ctx, out)
 }
 
 // DefaultAuthScopes reports the default set of authentication scopes to use with this package.
diff --git a/logging/apiv2/logging_client.go b/logging/apiv2/logging_client.go
index 4f64ff0..964d752 100644
--- a/logging/apiv2/logging_client.go
+++ b/logging/apiv2/logging_client.go
@@ -30,6 +30,7 @@
 	loggingpb "google.golang.org/genproto/googleapis/logging/v2"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/metadata"
 )
 
 // CallOptions contains the retry settings for each method of Client.
@@ -98,7 +99,7 @@
 	CallOptions *CallOptions
 
 	// The metadata to be sent with each request.
-	xGoogHeader []string
+	Metadata metadata.MD
 }
 
 // NewClient creates a new logging service v2 client.
@@ -136,7 +137,7 @@
 func (c *Client) SetGoogleClientInfo(keyval ...string) {
 	kv := append([]string{"gl-go", version.Go()}, keyval...)
 	kv = append(kv, "gapic", version.Repo, "gax", gax.Version, "grpc", grpc.Version)
-	c.xGoogHeader = []string{gax.XGoogHeader(kv...)}
+	c.Metadata = metadata.Pairs("x-goog-api-client", gax.XGoogHeader(kv...))
 }
 
 // ProjectPath returns the path for the project resource.
@@ -162,7 +163,7 @@
 // Log entries written shortly before the delete operation might not be
 // deleted.
 func (c *Client) DeleteLog(ctx context.Context, req *loggingpb.DeleteLogRequest, opts ...gax.CallOption) error {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.DeleteLog[0:len(c.CallOptions.DeleteLog):len(c.CallOptions.DeleteLog)], opts...)
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
 		var err error
@@ -172,9 +173,15 @@
 	return err
 }
 
-// WriteLogEntries writes log entries to Stackdriver Logging.
+// WriteLogEntries ## Log entry resources
+//
+// Writes log entries to Stackdriver Logging. This API method is the
+// only way to send log entries to Stackdriver Logging. This method
+// is used, directly or indirectly, by the Stackdriver Logging agent
+// (fluentd) and all logging libraries configured to use Stackdriver
+// Logging.
 func (c *Client) WriteLogEntries(ctx context.Context, req *loggingpb.WriteLogEntriesRequest, opts ...gax.CallOption) (*loggingpb.WriteLogEntriesResponse, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.WriteLogEntries[0:len(c.CallOptions.WriteLogEntries):len(c.CallOptions.WriteLogEntries)], opts...)
 	var resp *loggingpb.WriteLogEntriesResponse
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -192,7 +199,7 @@
 // Stackdriver Logging.  For ways to export log entries, see
 // Exporting Logs (at /logging/docs/export).
 func (c *Client) ListLogEntries(ctx context.Context, req *loggingpb.ListLogEntriesRequest, opts ...gax.CallOption) *LogEntryIterator {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.ListLogEntries[0:len(c.CallOptions.ListLogEntries):len(c.CallOptions.ListLogEntries)], opts...)
 	it := &LogEntryIterator{}
 	it.InternalFetch = func(pageSize int, pageToken string) ([]*loggingpb.LogEntry, string, error) {
@@ -228,7 +235,7 @@
 // ListMonitoredResourceDescriptors lists the descriptors for monitored resource types used by Stackdriver
 // Logging.
 func (c *Client) ListMonitoredResourceDescriptors(ctx context.Context, req *loggingpb.ListMonitoredResourceDescriptorsRequest, opts ...gax.CallOption) *MonitoredResourceDescriptorIterator {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.ListMonitoredResourceDescriptors[0:len(c.CallOptions.ListMonitoredResourceDescriptors):len(c.CallOptions.ListMonitoredResourceDescriptors)], opts...)
 	it := &MonitoredResourceDescriptorIterator{}
 	it.InternalFetch = func(pageSize int, pageToken string) ([]*monitoredrespb.MonitoredResourceDescriptor, string, error) {
@@ -264,7 +271,7 @@
 // ListLogs lists the logs in projects, organizations, folders, or billing accounts.
 // Only logs that have entries are listed.
 func (c *Client) ListLogs(ctx context.Context, req *loggingpb.ListLogsRequest, opts ...gax.CallOption) *StringIterator {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.ListLogs[0:len(c.CallOptions.ListLogs):len(c.CallOptions.ListLogs)], opts...)
 	it := &StringIterator{}
 	it.InternalFetch = func(pageSize int, pageToken string) ([]string, string, error) {
diff --git a/logging/apiv2/metrics_client.go b/logging/apiv2/metrics_client.go
index e4cc57f..3393290 100644
--- a/logging/apiv2/metrics_client.go
+++ b/logging/apiv2/metrics_client.go
@@ -29,6 +29,7 @@
 	loggingpb "google.golang.org/genproto/googleapis/logging/v2"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/metadata"
 )
 
 // MetricsCallOptions contains the retry settings for each method of MetricsClient.
@@ -84,7 +85,7 @@
 	CallOptions *MetricsCallOptions
 
 	// The metadata to be sent with each request.
-	xGoogHeader []string
+	Metadata metadata.MD
 }
 
 // NewMetricsClient creates a new metrics service v2 client.
@@ -122,7 +123,7 @@
 func (c *MetricsClient) SetGoogleClientInfo(keyval ...string) {
 	kv := append([]string{"gl-go", version.Go()}, keyval...)
 	kv = append(kv, "gapic", version.Repo, "gax", gax.Version, "grpc", grpc.Version)
-	c.xGoogHeader = []string{gax.XGoogHeader(kv...)}
+	c.Metadata = metadata.Pairs("x-goog-api-client", gax.XGoogHeader(kv...))
 }
 
 // MetricsProjectPath returns the path for the project resource.
@@ -145,7 +146,7 @@
 
 // ListLogMetrics lists logs-based metrics.
 func (c *MetricsClient) ListLogMetrics(ctx context.Context, req *loggingpb.ListLogMetricsRequest, opts ...gax.CallOption) *LogMetricIterator {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.ListLogMetrics[0:len(c.CallOptions.ListLogMetrics):len(c.CallOptions.ListLogMetrics)], opts...)
 	it := &LogMetricIterator{}
 	it.InternalFetch = func(pageSize int, pageToken string) ([]*loggingpb.LogMetric, string, error) {
@@ -180,7 +181,7 @@
 
 // GetLogMetric gets a logs-based metric.
 func (c *MetricsClient) GetLogMetric(ctx context.Context, req *loggingpb.GetLogMetricRequest, opts ...gax.CallOption) (*loggingpb.LogMetric, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.GetLogMetric[0:len(c.CallOptions.GetLogMetric):len(c.CallOptions.GetLogMetric)], opts...)
 	var resp *loggingpb.LogMetric
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -196,7 +197,7 @@
 
 // CreateLogMetric creates a logs-based metric.
 func (c *MetricsClient) CreateLogMetric(ctx context.Context, req *loggingpb.CreateLogMetricRequest, opts ...gax.CallOption) (*loggingpb.LogMetric, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.CreateLogMetric[0:len(c.CallOptions.CreateLogMetric):len(c.CallOptions.CreateLogMetric)], opts...)
 	var resp *loggingpb.LogMetric
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -212,7 +213,7 @@
 
 // UpdateLogMetric creates or updates a logs-based metric.
 func (c *MetricsClient) UpdateLogMetric(ctx context.Context, req *loggingpb.UpdateLogMetricRequest, opts ...gax.CallOption) (*loggingpb.LogMetric, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.UpdateLogMetric[0:len(c.CallOptions.UpdateLogMetric):len(c.CallOptions.UpdateLogMetric)], opts...)
 	var resp *loggingpb.LogMetric
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -228,7 +229,7 @@
 
 // DeleteLogMetric deletes a logs-based metric.
 func (c *MetricsClient) DeleteLogMetric(ctx context.Context, req *loggingpb.DeleteLogMetricRequest, opts ...gax.CallOption) error {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.DeleteLogMetric[0:len(c.CallOptions.DeleteLogMetric):len(c.CallOptions.DeleteLogMetric)], opts...)
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
 		var err error
diff --git a/logging/apiv2/mock_test.go b/logging/apiv2/mock_test.go
index 746dcd2..84be19c 100644
--- a/logging/apiv2/mock_test.go
+++ b/logging/apiv2/mock_test.go
@@ -20,6 +20,7 @@
 	emptypb "github.com/golang/protobuf/ptypes/empty"
 	monitoredrespb "google.golang.org/genproto/googleapis/api/monitoredres"
 	loggingpb "google.golang.org/genproto/googleapis/logging/v2"
+	field_maskpb "google.golang.org/genproto/protobuf/field_mask"
 )
 
 import (
@@ -197,6 +198,66 @@
 	return s.resps[0].(*emptypb.Empty), nil
 }
 
+func (s *mockConfigServer) ListExclusions(ctx context.Context, req *loggingpb.ListExclusionsRequest) (*loggingpb.ListExclusionsResponse, error) {
+	md, _ := metadata.FromIncomingContext(ctx)
+	if xg := md["x-goog-api-client"]; len(xg) == 0 || !strings.Contains(xg[0], "gl-go/") {
+		return nil, fmt.Errorf("x-goog-api-client = %v, expected gl-go key", xg)
+	}
+	s.reqs = append(s.reqs, req)
+	if s.err != nil {
+		return nil, s.err
+	}
+	return s.resps[0].(*loggingpb.ListExclusionsResponse), nil
+}
+
+func (s *mockConfigServer) GetExclusion(ctx context.Context, req *loggingpb.GetExclusionRequest) (*loggingpb.LogExclusion, error) {
+	md, _ := metadata.FromIncomingContext(ctx)
+	if xg := md["x-goog-api-client"]; len(xg) == 0 || !strings.Contains(xg[0], "gl-go/") {
+		return nil, fmt.Errorf("x-goog-api-client = %v, expected gl-go key", xg)
+	}
+	s.reqs = append(s.reqs, req)
+	if s.err != nil {
+		return nil, s.err
+	}
+	return s.resps[0].(*loggingpb.LogExclusion), nil
+}
+
+func (s *mockConfigServer) CreateExclusion(ctx context.Context, req *loggingpb.CreateExclusionRequest) (*loggingpb.LogExclusion, error) {
+	md, _ := metadata.FromIncomingContext(ctx)
+	if xg := md["x-goog-api-client"]; len(xg) == 0 || !strings.Contains(xg[0], "gl-go/") {
+		return nil, fmt.Errorf("x-goog-api-client = %v, expected gl-go key", xg)
+	}
+	s.reqs = append(s.reqs, req)
+	if s.err != nil {
+		return nil, s.err
+	}
+	return s.resps[0].(*loggingpb.LogExclusion), nil
+}
+
+func (s *mockConfigServer) UpdateExclusion(ctx context.Context, req *loggingpb.UpdateExclusionRequest) (*loggingpb.LogExclusion, error) {
+	md, _ := metadata.FromIncomingContext(ctx)
+	if xg := md["x-goog-api-client"]; len(xg) == 0 || !strings.Contains(xg[0], "gl-go/") {
+		return nil, fmt.Errorf("x-goog-api-client = %v, expected gl-go key", xg)
+	}
+	s.reqs = append(s.reqs, req)
+	if s.err != nil {
+		return nil, s.err
+	}
+	return s.resps[0].(*loggingpb.LogExclusion), nil
+}
+
+func (s *mockConfigServer) DeleteExclusion(ctx context.Context, req *loggingpb.DeleteExclusionRequest) (*emptypb.Empty, error) {
+	md, _ := metadata.FromIncomingContext(ctx)
+	if xg := md["x-goog-api-client"]; len(xg) == 0 || !strings.Contains(xg[0], "gl-go/") {
+		return nil, fmt.Errorf("x-goog-api-client = %v, expected gl-go key", xg)
+	}
+	s.reqs = append(s.reqs, req)
+	if s.err != nil {
+		return nil, s.err
+	}
+	return s.resps[0].(*emptypb.Empty), nil
+}
+
 type mockMetricsServer struct {
 	// Embed for forward compatibility.
 	// Tests will keep working if more methods are added
@@ -956,6 +1017,337 @@
 		t.Errorf("got error code %q, want %q", c, errCode)
 	}
 }
+func TestConfigServiceV2ListExclusions(t *testing.T) {
+	var nextPageToken string = ""
+	var exclusionsElement *loggingpb.LogExclusion = &loggingpb.LogExclusion{}
+	var exclusions = []*loggingpb.LogExclusion{exclusionsElement}
+	var expectedResponse = &loggingpb.ListExclusionsResponse{
+		NextPageToken: nextPageToken,
+		Exclusions:    exclusions,
+	}
+
+	mockConfig.err = nil
+	mockConfig.reqs = nil
+
+	mockConfig.resps = append(mockConfig.resps[:0], expectedResponse)
+
+	var formattedParent string = ConfigProjectPath("[PROJECT]")
+	var request = &loggingpb.ListExclusionsRequest{
+		Parent: formattedParent,
+	}
+
+	c, err := NewConfigClient(context.Background(), clientOpt)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	resp, err := c.ListExclusions(context.Background(), request).Next()
+
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if want, got := request, mockConfig.reqs[0]; !proto.Equal(want, got) {
+		t.Errorf("wrong request %q, want %q", got, want)
+	}
+
+	want := (interface{})(expectedResponse.Exclusions[0])
+	got := (interface{})(resp)
+	var ok bool
+
+	switch want := (want).(type) {
+	case proto.Message:
+		ok = proto.Equal(want, got.(proto.Message))
+	default:
+		ok = want == got
+	}
+	if !ok {
+		t.Errorf("wrong response %q, want %q)", got, want)
+	}
+}
+
+func TestConfigServiceV2ListExclusionsError(t *testing.T) {
+	errCode := codes.PermissionDenied
+	mockConfig.err = gstatus.Error(errCode, "test error")
+
+	var formattedParent string = ConfigProjectPath("[PROJECT]")
+	var request = &loggingpb.ListExclusionsRequest{
+		Parent: formattedParent,
+	}
+
+	c, err := NewConfigClient(context.Background(), clientOpt)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	resp, err := c.ListExclusions(context.Background(), request).Next()
+
+	if st, ok := gstatus.FromError(err); !ok {
+		t.Errorf("got error %v, expected grpc error", err)
+	} else if c := st.Code(); c != errCode {
+		t.Errorf("got error code %q, want %q", c, errCode)
+	}
+	_ = resp
+}
+func TestConfigServiceV2GetExclusion(t *testing.T) {
+	var name2 string = "name2-1052831874"
+	var description string = "description-1724546052"
+	var filter string = "filter-1274492040"
+	var disabled bool = true
+	var expectedResponse = &loggingpb.LogExclusion{
+		Name:        name2,
+		Description: description,
+		Filter:      filter,
+		Disabled:    disabled,
+	}
+
+	mockConfig.err = nil
+	mockConfig.reqs = nil
+
+	mockConfig.resps = append(mockConfig.resps[:0], expectedResponse)
+
+	var formattedName string = ConfigExclusionPath("[PROJECT]", "[EXCLUSION]")
+	var request = &loggingpb.GetExclusionRequest{
+		Name: formattedName,
+	}
+
+	c, err := NewConfigClient(context.Background(), clientOpt)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	resp, err := c.GetExclusion(context.Background(), request)
+
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if want, got := request, mockConfig.reqs[0]; !proto.Equal(want, got) {
+		t.Errorf("wrong request %q, want %q", got, want)
+	}
+
+	if want, got := expectedResponse, resp; !proto.Equal(want, got) {
+		t.Errorf("wrong response %q, want %q)", got, want)
+	}
+}
+
+func TestConfigServiceV2GetExclusionError(t *testing.T) {
+	errCode := codes.PermissionDenied
+	mockConfig.err = gstatus.Error(errCode, "test error")
+
+	var formattedName string = ConfigExclusionPath("[PROJECT]", "[EXCLUSION]")
+	var request = &loggingpb.GetExclusionRequest{
+		Name: formattedName,
+	}
+
+	c, err := NewConfigClient(context.Background(), clientOpt)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	resp, err := c.GetExclusion(context.Background(), request)
+
+	if st, ok := gstatus.FromError(err); !ok {
+		t.Errorf("got error %v, expected grpc error", err)
+	} else if c := st.Code(); c != errCode {
+		t.Errorf("got error code %q, want %q", c, errCode)
+	}
+	_ = resp
+}
+func TestConfigServiceV2CreateExclusion(t *testing.T) {
+	var name string = "name3373707"
+	var description string = "description-1724546052"
+	var filter string = "filter-1274492040"
+	var disabled bool = true
+	var expectedResponse = &loggingpb.LogExclusion{
+		Name:        name,
+		Description: description,
+		Filter:      filter,
+		Disabled:    disabled,
+	}
+
+	mockConfig.err = nil
+	mockConfig.reqs = nil
+
+	mockConfig.resps = append(mockConfig.resps[:0], expectedResponse)
+
+	var formattedParent string = ConfigProjectPath("[PROJECT]")
+	var exclusion *loggingpb.LogExclusion = &loggingpb.LogExclusion{}
+	var request = &loggingpb.CreateExclusionRequest{
+		Parent:    formattedParent,
+		Exclusion: exclusion,
+	}
+
+	c, err := NewConfigClient(context.Background(), clientOpt)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	resp, err := c.CreateExclusion(context.Background(), request)
+
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if want, got := request, mockConfig.reqs[0]; !proto.Equal(want, got) {
+		t.Errorf("wrong request %q, want %q", got, want)
+	}
+
+	if want, got := expectedResponse, resp; !proto.Equal(want, got) {
+		t.Errorf("wrong response %q, want %q)", got, want)
+	}
+}
+
+func TestConfigServiceV2CreateExclusionError(t *testing.T) {
+	errCode := codes.PermissionDenied
+	mockConfig.err = gstatus.Error(errCode, "test error")
+
+	var formattedParent string = ConfigProjectPath("[PROJECT]")
+	var exclusion *loggingpb.LogExclusion = &loggingpb.LogExclusion{}
+	var request = &loggingpb.CreateExclusionRequest{
+		Parent:    formattedParent,
+		Exclusion: exclusion,
+	}
+
+	c, err := NewConfigClient(context.Background(), clientOpt)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	resp, err := c.CreateExclusion(context.Background(), request)
+
+	if st, ok := gstatus.FromError(err); !ok {
+		t.Errorf("got error %v, expected grpc error", err)
+	} else if c := st.Code(); c != errCode {
+		t.Errorf("got error code %q, want %q", c, errCode)
+	}
+	_ = resp
+}
+func TestConfigServiceV2UpdateExclusion(t *testing.T) {
+	var name2 string = "name2-1052831874"
+	var description string = "description-1724546052"
+	var filter string = "filter-1274492040"
+	var disabled bool = true
+	var expectedResponse = &loggingpb.LogExclusion{
+		Name:        name2,
+		Description: description,
+		Filter:      filter,
+		Disabled:    disabled,
+	}
+
+	mockConfig.err = nil
+	mockConfig.reqs = nil
+
+	mockConfig.resps = append(mockConfig.resps[:0], expectedResponse)
+
+	var formattedName string = ConfigExclusionPath("[PROJECT]", "[EXCLUSION]")
+	var exclusion *loggingpb.LogExclusion = &loggingpb.LogExclusion{}
+	var updateMask *field_maskpb.FieldMask = &field_maskpb.FieldMask{}
+	var request = &loggingpb.UpdateExclusionRequest{
+		Name:       formattedName,
+		Exclusion:  exclusion,
+		UpdateMask: updateMask,
+	}
+
+	c, err := NewConfigClient(context.Background(), clientOpt)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	resp, err := c.UpdateExclusion(context.Background(), request)
+
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if want, got := request, mockConfig.reqs[0]; !proto.Equal(want, got) {
+		t.Errorf("wrong request %q, want %q", got, want)
+	}
+
+	if want, got := expectedResponse, resp; !proto.Equal(want, got) {
+		t.Errorf("wrong response %q, want %q)", got, want)
+	}
+}
+
+func TestConfigServiceV2UpdateExclusionError(t *testing.T) {
+	errCode := codes.PermissionDenied
+	mockConfig.err = gstatus.Error(errCode, "test error")
+
+	var formattedName string = ConfigExclusionPath("[PROJECT]", "[EXCLUSION]")
+	var exclusion *loggingpb.LogExclusion = &loggingpb.LogExclusion{}
+	var updateMask *field_maskpb.FieldMask = &field_maskpb.FieldMask{}
+	var request = &loggingpb.UpdateExclusionRequest{
+		Name:       formattedName,
+		Exclusion:  exclusion,
+		UpdateMask: updateMask,
+	}
+
+	c, err := NewConfigClient(context.Background(), clientOpt)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	resp, err := c.UpdateExclusion(context.Background(), request)
+
+	if st, ok := gstatus.FromError(err); !ok {
+		t.Errorf("got error %v, expected grpc error", err)
+	} else if c := st.Code(); c != errCode {
+		t.Errorf("got error code %q, want %q", c, errCode)
+	}
+	_ = resp
+}
+func TestConfigServiceV2DeleteExclusion(t *testing.T) {
+	var expectedResponse *emptypb.Empty = &emptypb.Empty{}
+
+	mockConfig.err = nil
+	mockConfig.reqs = nil
+
+	mockConfig.resps = append(mockConfig.resps[:0], expectedResponse)
+
+	var formattedName string = ConfigExclusionPath("[PROJECT]", "[EXCLUSION]")
+	var request = &loggingpb.DeleteExclusionRequest{
+		Name: formattedName,
+	}
+
+	c, err := NewConfigClient(context.Background(), clientOpt)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	err = c.DeleteExclusion(context.Background(), request)
+
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if want, got := request, mockConfig.reqs[0]; !proto.Equal(want, got) {
+		t.Errorf("wrong request %q, want %q", got, want)
+	}
+
+}
+
+func TestConfigServiceV2DeleteExclusionError(t *testing.T) {
+	errCode := codes.PermissionDenied
+	mockConfig.err = gstatus.Error(errCode, "test error")
+
+	var formattedName string = ConfigExclusionPath("[PROJECT]", "[EXCLUSION]")
+	var request = &loggingpb.DeleteExclusionRequest{
+		Name: formattedName,
+	}
+
+	c, err := NewConfigClient(context.Background(), clientOpt)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	err = c.DeleteExclusion(context.Background(), request)
+
+	if st, ok := gstatus.FromError(err); !ok {
+		t.Errorf("got error %v, expected grpc error", err)
+	} else if c := st.Code(); c != errCode {
+		t.Errorf("got error code %q, want %q", c, errCode)
+	}
+}
 func TestMetricsServiceV2ListLogMetrics(t *testing.T) {
 	var nextPageToken string = ""
 	var metricsElement *loggingpb.LogMetric = &loggingpb.LogMetric{}
@@ -1032,10 +1424,12 @@
 	var name string = "name3373707"
 	var description string = "description-1724546052"
 	var filter string = "filter-1274492040"
+	var valueExtractor string = "valueExtractor2047672534"
 	var expectedResponse = &loggingpb.LogMetric{
-		Name:        name,
-		Description: description,
-		Filter:      filter,
+		Name:           name,
+		Description:    description,
+		Filter:         filter,
+		ValueExtractor: valueExtractor,
 	}
 
 	mockMetrics.err = nil
@@ -1095,10 +1489,12 @@
 	var name string = "name3373707"
 	var description string = "description-1724546052"
 	var filter string = "filter-1274492040"
+	var valueExtractor string = "valueExtractor2047672534"
 	var expectedResponse = &loggingpb.LogMetric{
-		Name:        name,
-		Description: description,
-		Filter:      filter,
+		Name:           name,
+		Description:    description,
+		Filter:         filter,
+		ValueExtractor: valueExtractor,
 	}
 
 	mockMetrics.err = nil
@@ -1162,10 +1558,12 @@
 	var name string = "name3373707"
 	var description string = "description-1724546052"
 	var filter string = "filter-1274492040"
+	var valueExtractor string = "valueExtractor2047672534"
 	var expectedResponse = &loggingpb.LogMetric{
-		Name:        name,
-		Description: description,
-		Filter:      filter,
+		Name:           name,
+		Description:    description,
+		Filter:         filter,
+		ValueExtractor: valueExtractor,
 	}
 
 	mockMetrics.err = nil
diff --git a/longrunning/autogen/doc.go b/longrunning/autogen/doc.go
index 4958184..d75327a 100644
--- a/longrunning/autogen/doc.go
+++ b/longrunning/autogen/doc.go
@@ -14,9 +14,11 @@
 
 // AUTO-GENERATED CODE. DO NOT EDIT.
 
-// Package longrunning is an experimental, auto-generated package for the
+// Package longrunning is an auto-generated package for the
 // Google Long Running Operations API.
 //
+//   NOTE: This package is in alpha. It is not stable, and is likely to be subject to changes.
+//
 //
 // Use the client at cloud.google.com/go/longrunning in preference to this.
 package longrunning // import "cloud.google.com/go/longrunning/autogen"
@@ -26,11 +28,15 @@
 	"google.golang.org/grpc/metadata"
 )
 
-func insertXGoog(ctx context.Context, val []string) context.Context {
-	md, _ := metadata.FromOutgoingContext(ctx)
-	md = md.Copy()
-	md["x-goog-api-client"] = val
-	return metadata.NewOutgoingContext(ctx, md)
+func insertMetadata(ctx context.Context, mds ...metadata.MD) context.Context {
+	out, _ := metadata.FromOutgoingContext(ctx)
+	out = out.Copy()
+	for _, md := range mds {
+		for k, v := range md {
+			out[k] = append(out[k], v...)
+		}
+	}
+	return metadata.NewOutgoingContext(ctx, out)
 }
 
 // DefaultAuthScopes reports the default set of authentication scopes to use with this package.
diff --git a/longrunning/autogen/operations_client.go b/longrunning/autogen/operations_client.go
index 80cedf6..232979c 100644
--- a/longrunning/autogen/operations_client.go
+++ b/longrunning/autogen/operations_client.go
@@ -29,6 +29,7 @@
 	longrunningpb "google.golang.org/genproto/googleapis/longrunning"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/metadata"
 )
 
 // OperationsCallOptions contains the retry settings for each method of OperationsClient.
@@ -81,7 +82,7 @@
 	CallOptions *OperationsCallOptions
 
 	// The metadata to be sent with each request.
-	xGoogHeader []string
+	Metadata metadata.MD
 }
 
 // NewOperationsClient creates a new operations client.
@@ -127,14 +128,14 @@
 func (c *OperationsClient) SetGoogleClientInfo(keyval ...string) {
 	kv := append([]string{"gl-go", version.Go()}, keyval...)
 	kv = append(kv, "gapic", version.Repo, "gax", gax.Version, "grpc", grpc.Version)
-	c.xGoogHeader = []string{gax.XGoogHeader(kv...)}
+	c.Metadata = metadata.Pairs("x-goog-api-client", gax.XGoogHeader(kv...))
 }
 
 // GetOperation gets the latest state of a long-running operation.  Clients can use this
 // method to poll the operation result at intervals as recommended by the API
 // service.
 func (c *OperationsClient) GetOperation(ctx context.Context, req *longrunningpb.GetOperationRequest, opts ...gax.CallOption) (*longrunningpb.Operation, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.GetOperation[0:len(c.CallOptions.GetOperation):len(c.CallOptions.GetOperation)], opts...)
 	var resp *longrunningpb.Operation
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -154,7 +155,7 @@
 // NOTE: the name binding below allows API services to override the binding
 // to use different resource name schemes, such as users/*/operations.
 func (c *OperationsClient) ListOperations(ctx context.Context, req *longrunningpb.ListOperationsRequest, opts ...gax.CallOption) *OperationIterator {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.ListOperations[0:len(c.CallOptions.ListOperations):len(c.CallOptions.ListOperations)], opts...)
 	it := &OperationIterator{}
 	it.InternalFetch = func(pageSize int, pageToken string) ([]*longrunningpb.Operation, string, error) {
@@ -198,7 +199,7 @@
 // an [Operation.error][google.longrunning.Operation.error] value with a [google.rpc.Status.code][google.rpc.Status.code] of 1,
 // corresponding to Code.CANCELLED.
 func (c *OperationsClient) CancelOperation(ctx context.Context, req *longrunningpb.CancelOperationRequest, opts ...gax.CallOption) error {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.CancelOperation[0:len(c.CallOptions.CancelOperation):len(c.CallOptions.CancelOperation)], opts...)
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
 		var err error
@@ -213,7 +214,7 @@
 // operation. If the server doesn't support this method, it returns
 // google.rpc.Code.UNIMPLEMENTED.
 func (c *OperationsClient) DeleteOperation(ctx context.Context, req *longrunningpb.DeleteOperationRequest, opts ...gax.CallOption) error {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.DeleteOperation[0:len(c.CallOptions.DeleteOperation):len(c.CallOptions.DeleteOperation)], opts...)
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
 		var err error
diff --git a/monitoring/apiv3/doc.go b/monitoring/apiv3/doc.go
index 426f6a5..7dca517 100644
--- a/monitoring/apiv3/doc.go
+++ b/monitoring/apiv3/doc.go
@@ -14,9 +14,11 @@
 
 // AUTO-GENERATED CODE. DO NOT EDIT.
 
-// Package monitoring is an experimental, auto-generated package for the
+// Package monitoring is an auto-generated package for the
 // Stackdriver Monitoring API.
 //
+//   NOTE: This package is in alpha. It is not stable, and is likely to be subject to changes.
+//
 // Manages your Stackdriver Monitoring data and configurations. Most projects
 // must be associated with a Stackdriver account, with a few exceptions as
 // noted on the individual method pages.
@@ -27,11 +29,15 @@
 	"google.golang.org/grpc/metadata"
 )
 
-func insertXGoog(ctx context.Context, val []string) context.Context {
-	md, _ := metadata.FromOutgoingContext(ctx)
-	md = md.Copy()
-	md["x-goog-api-client"] = val
-	return metadata.NewOutgoingContext(ctx, md)
+func insertMetadata(ctx context.Context, mds ...metadata.MD) context.Context {
+	out, _ := metadata.FromOutgoingContext(ctx)
+	out = out.Copy()
+	for _, md := range mds {
+		for k, v := range md {
+			out[k] = append(out[k], v...)
+		}
+	}
+	return metadata.NewOutgoingContext(ctx, out)
 }
 
 // DefaultAuthScopes reports the default set of authentication scopes to use with this package.
diff --git a/monitoring/apiv3/group_client.go b/monitoring/apiv3/group_client.go
index d235c85..70becdd 100644
--- a/monitoring/apiv3/group_client.go
+++ b/monitoring/apiv3/group_client.go
@@ -30,6 +30,7 @@
 	monitoringpb "google.golang.org/genproto/googleapis/monitoring/v3"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/metadata"
 )
 
 // GroupCallOptions contains the retry settings for each method of GroupClient.
@@ -86,7 +87,7 @@
 	CallOptions *GroupCallOptions
 
 	// The metadata to be sent with each request.
-	xGoogHeader []string
+	Metadata metadata.MD
 }
 
 // NewGroupClient creates a new group service client.
@@ -135,7 +136,7 @@
 func (c *GroupClient) setGoogleClientInfo(keyval ...string) {
 	kv := append([]string{"gl-go", version.Go()}, keyval...)
 	kv = append(kv, "gapic", version.Repo, "gax", gax.Version, "grpc", grpc.Version)
-	c.xGoogHeader = []string{gax.XGoogHeader(kv...)}
+	c.Metadata = metadata.Pairs("x-goog-api-client", gax.XGoogHeader(kv...))
 }
 
 // GroupProjectPath returns the path for the project resource.
@@ -158,7 +159,7 @@
 
 // ListGroups lists the existing groups.
 func (c *GroupClient) ListGroups(ctx context.Context, req *monitoringpb.ListGroupsRequest, opts ...gax.CallOption) *GroupIterator {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.ListGroups[0:len(c.CallOptions.ListGroups):len(c.CallOptions.ListGroups)], opts...)
 	it := &GroupIterator{}
 	it.InternalFetch = func(pageSize int, pageToken string) ([]*monitoringpb.Group, string, error) {
@@ -193,7 +194,7 @@
 
 // GetGroup gets a single group.
 func (c *GroupClient) GetGroup(ctx context.Context, req *monitoringpb.GetGroupRequest, opts ...gax.CallOption) (*monitoringpb.Group, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.GetGroup[0:len(c.CallOptions.GetGroup):len(c.CallOptions.GetGroup)], opts...)
 	var resp *monitoringpb.Group
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -209,7 +210,7 @@
 
 // CreateGroup creates a new group.
 func (c *GroupClient) CreateGroup(ctx context.Context, req *monitoringpb.CreateGroupRequest, opts ...gax.CallOption) (*monitoringpb.Group, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.CreateGroup[0:len(c.CallOptions.CreateGroup):len(c.CallOptions.CreateGroup)], opts...)
 	var resp *monitoringpb.Group
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -226,7 +227,7 @@
 // UpdateGroup updates an existing group.
 // You can change any group attributes except name.
 func (c *GroupClient) UpdateGroup(ctx context.Context, req *monitoringpb.UpdateGroupRequest, opts ...gax.CallOption) (*monitoringpb.Group, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.UpdateGroup[0:len(c.CallOptions.UpdateGroup):len(c.CallOptions.UpdateGroup)], opts...)
 	var resp *monitoringpb.Group
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -242,7 +243,7 @@
 
 // DeleteGroup deletes an existing group.
 func (c *GroupClient) DeleteGroup(ctx context.Context, req *monitoringpb.DeleteGroupRequest, opts ...gax.CallOption) error {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.DeleteGroup[0:len(c.CallOptions.DeleteGroup):len(c.CallOptions.DeleteGroup)], opts...)
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
 		var err error
@@ -254,7 +255,7 @@
 
 // ListGroupMembers lists the monitored resources that are members of a group.
 func (c *GroupClient) ListGroupMembers(ctx context.Context, req *monitoringpb.ListGroupMembersRequest, opts ...gax.CallOption) *MonitoredResourceIterator {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.ListGroupMembers[0:len(c.CallOptions.ListGroupMembers):len(c.CallOptions.ListGroupMembers)], opts...)
 	it := &MonitoredResourceIterator{}
 	it.InternalFetch = func(pageSize int, pageToken string) ([]*monitoredrespb.MonitoredResource, string, error) {
diff --git a/monitoring/apiv3/metric_client.go b/monitoring/apiv3/metric_client.go
index 8b35ce7..24b1422 100644
--- a/monitoring/apiv3/metric_client.go
+++ b/monitoring/apiv3/metric_client.go
@@ -31,6 +31,7 @@
 	monitoringpb "google.golang.org/genproto/googleapis/monitoring/v3"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/metadata"
 )
 
 // MetricCallOptions contains the retry settings for each method of MetricClient.
@@ -91,7 +92,7 @@
 	CallOptions *MetricCallOptions
 
 	// The metadata to be sent with each request.
-	xGoogHeader []string
+	Metadata metadata.MD
 }
 
 // NewMetricClient creates a new metric service client.
@@ -130,7 +131,7 @@
 func (c *MetricClient) setGoogleClientInfo(keyval ...string) {
 	kv := append([]string{"gl-go", version.Go()}, keyval...)
 	kv = append(kv, "gapic", version.Repo, "gax", gax.Version, "grpc", grpc.Version)
-	c.xGoogHeader = []string{gax.XGoogHeader(kv...)}
+	c.Metadata = metadata.Pairs("x-goog-api-client", gax.XGoogHeader(kv...))
 }
 
 // MetricProjectPath returns the path for the project resource.
@@ -163,7 +164,7 @@
 
 // ListMonitoredResourceDescriptors lists monitored resource descriptors that match a filter. This method does not require a Stackdriver account.
 func (c *MetricClient) ListMonitoredResourceDescriptors(ctx context.Context, req *monitoringpb.ListMonitoredResourceDescriptorsRequest, opts ...gax.CallOption) *MonitoredResourceDescriptorIterator {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.ListMonitoredResourceDescriptors[0:len(c.CallOptions.ListMonitoredResourceDescriptors):len(c.CallOptions.ListMonitoredResourceDescriptors)], opts...)
 	it := &MonitoredResourceDescriptorIterator{}
 	it.InternalFetch = func(pageSize int, pageToken string) ([]*monitoredrespb.MonitoredResourceDescriptor, string, error) {
@@ -198,7 +199,7 @@
 
 // GetMonitoredResourceDescriptor gets a single monitored resource descriptor. This method does not require a Stackdriver account.
 func (c *MetricClient) GetMonitoredResourceDescriptor(ctx context.Context, req *monitoringpb.GetMonitoredResourceDescriptorRequest, opts ...gax.CallOption) (*monitoredrespb.MonitoredResourceDescriptor, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.GetMonitoredResourceDescriptor[0:len(c.CallOptions.GetMonitoredResourceDescriptor):len(c.CallOptions.GetMonitoredResourceDescriptor)], opts...)
 	var resp *monitoredrespb.MonitoredResourceDescriptor
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -214,7 +215,7 @@
 
 // ListMetricDescriptors lists metric descriptors that match a filter. This method does not require a Stackdriver account.
 func (c *MetricClient) ListMetricDescriptors(ctx context.Context, req *monitoringpb.ListMetricDescriptorsRequest, opts ...gax.CallOption) *MetricDescriptorIterator {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.ListMetricDescriptors[0:len(c.CallOptions.ListMetricDescriptors):len(c.CallOptions.ListMetricDescriptors)], opts...)
 	it := &MetricDescriptorIterator{}
 	it.InternalFetch = func(pageSize int, pageToken string) ([]*metricpb.MetricDescriptor, string, error) {
@@ -249,7 +250,7 @@
 
 // GetMetricDescriptor gets a single metric descriptor. This method does not require a Stackdriver account.
 func (c *MetricClient) GetMetricDescriptor(ctx context.Context, req *monitoringpb.GetMetricDescriptorRequest, opts ...gax.CallOption) (*metricpb.MetricDescriptor, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.GetMetricDescriptor[0:len(c.CallOptions.GetMetricDescriptor):len(c.CallOptions.GetMetricDescriptor)], opts...)
 	var resp *metricpb.MetricDescriptor
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -267,7 +268,7 @@
 // User-created metric descriptors define
 // custom metrics (at /monitoring/custom-metrics).
 func (c *MetricClient) CreateMetricDescriptor(ctx context.Context, req *monitoringpb.CreateMetricDescriptorRequest, opts ...gax.CallOption) (*metricpb.MetricDescriptor, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.CreateMetricDescriptor[0:len(c.CallOptions.CreateMetricDescriptor):len(c.CallOptions.CreateMetricDescriptor)], opts...)
 	var resp *metricpb.MetricDescriptor
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -284,7 +285,7 @@
 // DeleteMetricDescriptor deletes a metric descriptor. Only user-created
 // custom metrics (at /monitoring/custom-metrics) can be deleted.
 func (c *MetricClient) DeleteMetricDescriptor(ctx context.Context, req *monitoringpb.DeleteMetricDescriptorRequest, opts ...gax.CallOption) error {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.DeleteMetricDescriptor[0:len(c.CallOptions.DeleteMetricDescriptor):len(c.CallOptions.DeleteMetricDescriptor)], opts...)
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
 		var err error
@@ -296,7 +297,7 @@
 
 // ListTimeSeries lists time series that match a filter. This method does not require a Stackdriver account.
 func (c *MetricClient) ListTimeSeries(ctx context.Context, req *monitoringpb.ListTimeSeriesRequest, opts ...gax.CallOption) *TimeSeriesIterator {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.ListTimeSeries[0:len(c.CallOptions.ListTimeSeries):len(c.CallOptions.ListTimeSeries)], opts...)
 	it := &TimeSeriesIterator{}
 	it.InternalFetch = func(pageSize int, pageToken string) ([]*monitoringpb.TimeSeries, string, error) {
@@ -334,7 +335,7 @@
 // If any time series could not be written, a corresponding failure message is
 // included in the error response.
 func (c *MetricClient) CreateTimeSeries(ctx context.Context, req *monitoringpb.CreateTimeSeriesRequest, opts ...gax.CallOption) error {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.CreateTimeSeries[0:len(c.CallOptions.CreateTimeSeries):len(c.CallOptions.CreateTimeSeries)], opts...)
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
 		var err error
diff --git a/pubsub/apiv1/doc.go b/pubsub/apiv1/doc.go
index c15769b..d34d06e 100644
--- a/pubsub/apiv1/doc.go
+++ b/pubsub/apiv1/doc.go
@@ -14,9 +14,11 @@
 
 // AUTO-GENERATED CODE. DO NOT EDIT.
 
-// Package pubsub is an experimental, auto-generated package for the
+// Package pubsub is an auto-generated package for the
 // Google Cloud Pub/Sub API.
 //
+//   NOTE: This package is in alpha. It is not stable, and is likely to be subject to changes.
+//
 // Provides reliable, many-to-many, asynchronous messaging between
 // applications.
 //
@@ -28,11 +30,15 @@
 	"google.golang.org/grpc/metadata"
 )
 
-func insertXGoog(ctx context.Context, val []string) context.Context {
-	md, _ := metadata.FromOutgoingContext(ctx)
-	md = md.Copy()
-	md["x-goog-api-client"] = val
-	return metadata.NewOutgoingContext(ctx, md)
+func insertMetadata(ctx context.Context, mds ...metadata.MD) context.Context {
+	out, _ := metadata.FromOutgoingContext(ctx)
+	out = out.Copy()
+	for _, md := range mds {
+		for k, v := range md {
+			out[k] = append(out[k], v...)
+		}
+	}
+	return metadata.NewOutgoingContext(ctx, out)
 }
 
 // DefaultAuthScopes reports the default set of authentication scopes to use with this package.
diff --git a/pubsub/apiv1/publisher_client.go b/pubsub/apiv1/publisher_client.go
index eab21d8..6088dac 100644
--- a/pubsub/apiv1/publisher_client.go
+++ b/pubsub/apiv1/publisher_client.go
@@ -30,6 +30,7 @@
 	pubsubpb "google.golang.org/genproto/googleapis/pubsub/v1"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/metadata"
 )
 
 // PublisherCallOptions contains the retry settings for each method of PublisherClient.
@@ -67,13 +68,13 @@
 		{"messaging", "one_plus_delivery"}: {
 			gax.WithRetry(func() gax.Retryer {
 				return gax.OnCodes([]codes.Code{
-					codes.Canceled,
-					codes.Unknown,
-					codes.DeadlineExceeded,
-					codes.ResourceExhausted,
 					codes.Aborted,
+					codes.Canceled,
+					codes.DeadlineExceeded,
 					codes.Internal,
+					codes.ResourceExhausted,
 					codes.Unavailable,
+					codes.Unknown,
 				}, gax.Backoff{
 					Initial:    100 * time.Millisecond,
 					Max:        60000 * time.Millisecond,
@@ -105,7 +106,7 @@
 	CallOptions *PublisherCallOptions
 
 	// The metadata to be sent with each request.
-	xGoogHeader []string
+	Metadata metadata.MD
 }
 
 // NewPublisherClient creates a new publisher client.
@@ -144,7 +145,7 @@
 func (c *PublisherClient) SetGoogleClientInfo(keyval ...string) {
 	kv := append([]string{"gl-go", version.Go()}, keyval...)
 	kv = append(kv, "gapic", version.Repo, "gax", gax.Version, "grpc", grpc.Version)
-	c.xGoogHeader = []string{gax.XGoogHeader(kv...)}
+	c.Metadata = metadata.Pairs("x-goog-api-client", gax.XGoogHeader(kv...))
 }
 
 // PublisherProjectPath returns the path for the project resource.
@@ -175,7 +176,7 @@
 
 // CreateTopic creates the given topic with the given name.
 func (c *PublisherClient) CreateTopic(ctx context.Context, req *pubsubpb.Topic, opts ...gax.CallOption) (*pubsubpb.Topic, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.CreateTopic[0:len(c.CallOptions.CreateTopic):len(c.CallOptions.CreateTopic)], opts...)
 	var resp *pubsubpb.Topic
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -196,7 +197,7 @@
 // corrected in V2.  See
 // https://cloud.google.com/apis/design/standard_methods#update for details.
 func (c *PublisherClient) UpdateTopic(ctx context.Context, req *pubsubpb.UpdateTopicRequest, opts ...gax.CallOption) (*pubsubpb.Topic, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.UpdateTopic[0:len(c.CallOptions.UpdateTopic):len(c.CallOptions.UpdateTopic)], opts...)
 	var resp *pubsubpb.Topic
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -214,7 +215,7 @@
 // does not exist. The message payload must not be empty; it must contain
 // either a non-empty data field, or at least one attribute.
 func (c *PublisherClient) Publish(ctx context.Context, req *pubsubpb.PublishRequest, opts ...gax.CallOption) (*pubsubpb.PublishResponse, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.Publish[0:len(c.CallOptions.Publish):len(c.CallOptions.Publish)], opts...)
 	var resp *pubsubpb.PublishResponse
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -230,7 +231,7 @@
 
 // GetTopic gets the configuration of a topic.
 func (c *PublisherClient) GetTopic(ctx context.Context, req *pubsubpb.GetTopicRequest, opts ...gax.CallOption) (*pubsubpb.Topic, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.GetTopic[0:len(c.CallOptions.GetTopic):len(c.CallOptions.GetTopic)], opts...)
 	var resp *pubsubpb.Topic
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -246,7 +247,7 @@
 
 // ListTopics lists matching topics.
 func (c *PublisherClient) ListTopics(ctx context.Context, req *pubsubpb.ListTopicsRequest, opts ...gax.CallOption) *TopicIterator {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.ListTopics[0:len(c.CallOptions.ListTopics):len(c.CallOptions.ListTopics)], opts...)
 	it := &TopicIterator{}
 	it.InternalFetch = func(pageSize int, pageToken string) ([]*pubsubpb.Topic, string, error) {
@@ -281,7 +282,7 @@
 
 // ListTopicSubscriptions lists the name of the subscriptions for this topic.
 func (c *PublisherClient) ListTopicSubscriptions(ctx context.Context, req *pubsubpb.ListTopicSubscriptionsRequest, opts ...gax.CallOption) *StringIterator {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.ListTopicSubscriptions[0:len(c.CallOptions.ListTopicSubscriptions):len(c.CallOptions.ListTopicSubscriptions)], opts...)
 	it := &StringIterator{}
 	it.InternalFetch = func(pageSize int, pageToken string) ([]string, string, error) {
@@ -320,7 +321,7 @@
 // configuration or subscriptions. Existing subscriptions to this topic are
 // not deleted, but their topic field is set to _deleted-topic_.
 func (c *PublisherClient) DeleteTopic(ctx context.Context, req *pubsubpb.DeleteTopicRequest, opts ...gax.CallOption) error {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.DeleteTopic[0:len(c.CallOptions.DeleteTopic):len(c.CallOptions.DeleteTopic)], opts...)
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
 		var err error
diff --git a/pubsub/apiv1/subscriber_client.go b/pubsub/apiv1/subscriber_client.go
index eb6f380..574c07d 100644
--- a/pubsub/apiv1/subscriber_client.go
+++ b/pubsub/apiv1/subscriber_client.go
@@ -30,6 +30,7 @@
 	pubsubpb "google.golang.org/genproto/googleapis/pubsub/v1"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/metadata"
 )
 
 // SubscriberCallOptions contains the retry settings for each method of SubscriberClient.
@@ -77,8 +78,8 @@
 				return gax.OnCodes([]codes.Code{
 					codes.Canceled,
 					codes.DeadlineExceeded,
-					codes.ResourceExhausted,
 					codes.Internal,
+					codes.ResourceExhausted,
 					codes.Unavailable,
 				}, gax.Backoff{
 					Initial:    100 * time.Millisecond,
@@ -92,8 +93,8 @@
 				return gax.OnCodes([]codes.Code{
 					codes.Canceled,
 					codes.DeadlineExceeded,
-					codes.ResourceExhausted,
 					codes.Internal,
+					codes.ResourceExhausted,
 					codes.Unavailable,
 				}, gax.Backoff{
 					Initial:    100 * time.Millisecond,
@@ -134,7 +135,7 @@
 	CallOptions *SubscriberCallOptions
 
 	// The metadata to be sent with each request.
-	xGoogHeader []string
+	Metadata metadata.MD
 }
 
 // NewSubscriberClient creates a new subscriber client.
@@ -173,7 +174,7 @@
 func (c *SubscriberClient) SetGoogleClientInfo(keyval ...string) {
 	kv := append([]string{"gl-go", version.Go()}, keyval...)
 	kv = append(kv, "gapic", version.Repo, "gax", gax.Version, "grpc", grpc.Version)
-	c.xGoogHeader = []string{gax.XGoogHeader(kv...)}
+	c.Metadata = metadata.Pairs("x-goog-api-client", gax.XGoogHeader(kv...))
 }
 
 // SubscriberProjectPath returns the path for the project resource.
@@ -233,7 +234,7 @@
 // The generated name is populated in the returned Subscription object.
 // Note that for REST API requests, you must specify a name in the request.
 func (c *SubscriberClient) CreateSubscription(ctx context.Context, req *pubsubpb.Subscription, opts ...gax.CallOption) (*pubsubpb.Subscription, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.CreateSubscription[0:len(c.CallOptions.CreateSubscription):len(c.CallOptions.CreateSubscription)], opts...)
 	var resp *pubsubpb.Subscription
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -249,7 +250,7 @@
 
 // GetSubscription gets the configuration details of a subscription.
 func (c *SubscriberClient) GetSubscription(ctx context.Context, req *pubsubpb.GetSubscriptionRequest, opts ...gax.CallOption) (*pubsubpb.Subscription, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.GetSubscription[0:len(c.CallOptions.GetSubscription):len(c.CallOptions.GetSubscription)], opts...)
 	var resp *pubsubpb.Subscription
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -270,7 +271,7 @@
 // corrected in V2.  See
 // https://cloud.google.com/apis/design/standard_methods#update for details.
 func (c *SubscriberClient) UpdateSubscription(ctx context.Context, req *pubsubpb.UpdateSubscriptionRequest, opts ...gax.CallOption) (*pubsubpb.Subscription, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.UpdateSubscription[0:len(c.CallOptions.UpdateSubscription):len(c.CallOptions.UpdateSubscription)], opts...)
 	var resp *pubsubpb.Subscription
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -286,7 +287,7 @@
 
 // ListSubscriptions lists matching subscriptions.
 func (c *SubscriberClient) ListSubscriptions(ctx context.Context, req *pubsubpb.ListSubscriptionsRequest, opts ...gax.CallOption) *SubscriptionIterator {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.ListSubscriptions[0:len(c.CallOptions.ListSubscriptions):len(c.CallOptions.ListSubscriptions)], opts...)
 	it := &SubscriptionIterator{}
 	it.InternalFetch = func(pageSize int, pageToken string) ([]*pubsubpb.Subscription, string, error) {
@@ -325,7 +326,7 @@
 // the same name, but the new one has no association with the old
 // subscription or its topic unless the same topic is specified.
 func (c *SubscriberClient) DeleteSubscription(ctx context.Context, req *pubsubpb.DeleteSubscriptionRequest, opts ...gax.CallOption) error {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.DeleteSubscription[0:len(c.CallOptions.DeleteSubscription):len(c.CallOptions.DeleteSubscription)], opts...)
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
 		var err error
@@ -341,7 +342,7 @@
 // processing was interrupted. Note that this does not modify the
 // subscription-level ackDeadlineSeconds used for subsequent messages.
 func (c *SubscriberClient) ModifyAckDeadline(ctx context.Context, req *pubsubpb.ModifyAckDeadlineRequest, opts ...gax.CallOption) error {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.ModifyAckDeadline[0:len(c.CallOptions.ModifyAckDeadline):len(c.CallOptions.ModifyAckDeadline)], opts...)
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
 		var err error
@@ -359,7 +360,7 @@
 // but such a message may be redelivered later. Acknowledging a message more
 // than once will not result in an error.
 func (c *SubscriberClient) Acknowledge(ctx context.Context, req *pubsubpb.AcknowledgeRequest, opts ...gax.CallOption) error {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.Acknowledge[0:len(c.CallOptions.Acknowledge):len(c.CallOptions.Acknowledge)], opts...)
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
 		var err error
@@ -374,7 +375,7 @@
 // there are too many concurrent pull requests pending for the given
 // subscription.
 func (c *SubscriberClient) Pull(ctx context.Context, req *pubsubpb.PullRequest, opts ...gax.CallOption) (*pubsubpb.PullResponse, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.Pull[0:len(c.CallOptions.Pull):len(c.CallOptions.Pull)], opts...)
 	var resp *pubsubpb.PullResponse
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -401,7 +402,7 @@
 // (e.g., a server restart). These should also be retried by the client. Flow
 // control can be achieved by configuring the underlying RPC channel.
 func (c *SubscriberClient) StreamingPull(ctx context.Context, opts ...gax.CallOption) (pubsubpb.Subscriber_StreamingPullClient, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.StreamingPull[0:len(c.CallOptions.StreamingPull):len(c.CallOptions.StreamingPull)], opts...)
 	var resp pubsubpb.Subscriber_StreamingPullClient
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -422,7 +423,7 @@
 // attributes of a push subscription. Messages will accumulate for delivery
 // continuously through the call regardless of changes to the PushConfig.
 func (c *SubscriberClient) ModifyPushConfig(ctx context.Context, req *pubsubpb.ModifyPushConfigRequest, opts ...gax.CallOption) error {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.ModifyPushConfig[0:len(c.CallOptions.ModifyPushConfig):len(c.CallOptions.ModifyPushConfig)], opts...)
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
 		var err error
@@ -434,7 +435,7 @@
 
 // ListSnapshots lists the existing snapshots.
 func (c *SubscriberClient) ListSnapshots(ctx context.Context, req *pubsubpb.ListSnapshotsRequest, opts ...gax.CallOption) *SnapshotIterator {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.ListSnapshots[0:len(c.CallOptions.ListSnapshots):len(c.CallOptions.ListSnapshots)], opts...)
 	it := &SnapshotIterator{}
 	it.InternalFetch = func(pageSize int, pageToken string) ([]*pubsubpb.Snapshot, string, error) {
@@ -478,7 +479,7 @@
 // The generated name is populated in the returned Snapshot object.
 // Note that for REST API requests, you must specify a name in the request.
 func (c *SubscriberClient) CreateSnapshot(ctx context.Context, req *pubsubpb.CreateSnapshotRequest, opts ...gax.CallOption) (*pubsubpb.Snapshot, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.CreateSnapshot[0:len(c.CallOptions.CreateSnapshot):len(c.CallOptions.CreateSnapshot)], opts...)
 	var resp *pubsubpb.Snapshot
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -499,7 +500,7 @@
 // corrected in V2.  See
 // https://cloud.google.com/apis/design/standard_methods#update for details.
 func (c *SubscriberClient) UpdateSnapshot(ctx context.Context, req *pubsubpb.UpdateSnapshotRequest, opts ...gax.CallOption) (*pubsubpb.Snapshot, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.UpdateSnapshot[0:len(c.CallOptions.UpdateSnapshot):len(c.CallOptions.UpdateSnapshot)], opts...)
 	var resp *pubsubpb.Snapshot
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -518,7 +519,7 @@
 // created with the same name, but the new one has no association with the old
 // snapshot or its subscription, unless the same subscription is specified.
 func (c *SubscriberClient) DeleteSnapshot(ctx context.Context, req *pubsubpb.DeleteSnapshotRequest, opts ...gax.CallOption) error {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.DeleteSnapshot[0:len(c.CallOptions.DeleteSnapshot):len(c.CallOptions.DeleteSnapshot)], opts...)
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
 		var err error
@@ -531,7 +532,7 @@
 // Seek seeks an existing subscription to a point in time or to a given snapshot,
 // whichever is provided in the request.
 func (c *SubscriberClient) Seek(ctx context.Context, req *pubsubpb.SeekRequest, opts ...gax.CallOption) (*pubsubpb.SeekResponse, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.Seek[0:len(c.CallOptions.Seek):len(c.CallOptions.Seek)], opts...)
 	var resp *pubsubpb.SeekResponse
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
diff --git a/spanner/admin/database/apiv1/database_admin_client.go b/spanner/admin/database/apiv1/database_admin_client.go
index b256ebc..ba01a89 100644
--- a/spanner/admin/database/apiv1/database_admin_client.go
+++ b/spanner/admin/database/apiv1/database_admin_client.go
@@ -33,6 +33,7 @@
 	databasepb "google.golang.org/genproto/googleapis/spanner/admin/database/v1"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/metadata"
 )
 
 // DatabaseAdminCallOptions contains the retry settings for each method of DatabaseAdminClient.
@@ -100,7 +101,7 @@
 	CallOptions *DatabaseAdminCallOptions
 
 	// The metadata to be sent with each request.
-	xGoogHeader []string
+	Metadata metadata.MD
 }
 
 // NewDatabaseAdminClient creates a new database admin client.
@@ -153,7 +154,7 @@
 func (c *DatabaseAdminClient) setGoogleClientInfo(keyval ...string) {
 	kv := append([]string{"gl-go", version.Go()}, keyval...)
 	kv = append(kv, "gapic", version.Repo, "gax", gax.Version, "grpc", grpc.Version)
-	c.xGoogHeader = []string{gax.XGoogHeader(kv...)}
+	c.Metadata = metadata.Pairs("x-goog-api-client", gax.XGoogHeader(kv...))
 }
 
 // DatabaseAdminInstancePath returns the path for the instance resource.
@@ -180,7 +181,7 @@
 
 // ListDatabases lists Cloud Spanner databases.
 func (c *DatabaseAdminClient) ListDatabases(ctx context.Context, req *databasepb.ListDatabasesRequest, opts ...gax.CallOption) *DatabaseIterator {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.ListDatabases[0:len(c.CallOptions.ListDatabases):len(c.CallOptions.ListDatabases)], opts...)
 	it := &DatabaseIterator{}
 	it.InternalFetch = func(pageSize int, pageToken string) ([]*databasepb.Database, string, error) {
@@ -222,7 +223,7 @@
 // [response][google.longrunning.Operation.response] field type is
 // [Database][google.spanner.admin.database.v1.Database], if successful.
 func (c *DatabaseAdminClient) CreateDatabase(ctx context.Context, req *databasepb.CreateDatabaseRequest, opts ...gax.CallOption) (*CreateDatabaseOperation, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.CreateDatabase[0:len(c.CallOptions.CreateDatabase):len(c.CallOptions.CreateDatabase)], opts...)
 	var resp *longrunningpb.Operation
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -240,7 +241,7 @@
 
 // GetDatabase gets the state of a Cloud Spanner database.
 func (c *DatabaseAdminClient) GetDatabase(ctx context.Context, req *databasepb.GetDatabaseRequest, opts ...gax.CallOption) (*databasepb.Database, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.GetDatabase[0:len(c.CallOptions.GetDatabase):len(c.CallOptions.GetDatabase)], opts...)
 	var resp *databasepb.Database
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -262,7 +263,7 @@
 // [metadata][google.longrunning.Operation.metadata] field type is
 // [UpdateDatabaseDdlMetadata][google.spanner.admin.database.v1.UpdateDatabaseDdlMetadata].  The operation has no response.
 func (c *DatabaseAdminClient) UpdateDatabaseDdl(ctx context.Context, req *databasepb.UpdateDatabaseDdlRequest, opts ...gax.CallOption) (*UpdateDatabaseDdlOperation, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.UpdateDatabaseDdl[0:len(c.CallOptions.UpdateDatabaseDdl):len(c.CallOptions.UpdateDatabaseDdl)], opts...)
 	var resp *longrunningpb.Operation
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -280,7 +281,7 @@
 
 // DropDatabase drops (aka deletes) a Cloud Spanner database.
 func (c *DatabaseAdminClient) DropDatabase(ctx context.Context, req *databasepb.DropDatabaseRequest, opts ...gax.CallOption) error {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.DropDatabase[0:len(c.CallOptions.DropDatabase):len(c.CallOptions.DropDatabase)], opts...)
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
 		var err error
@@ -294,7 +295,7 @@
 // DDL statements. This method does not show pending schema updates, those may
 // be queried using the [Operations][google.longrunning.Operations] API.
 func (c *DatabaseAdminClient) GetDatabaseDdl(ctx context.Context, req *databasepb.GetDatabaseDdlRequest, opts ...gax.CallOption) (*databasepb.GetDatabaseDdlResponse, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.GetDatabaseDdl[0:len(c.CallOptions.GetDatabaseDdl):len(c.CallOptions.GetDatabaseDdl)], opts...)
 	var resp *databasepb.GetDatabaseDdlResponse
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -314,7 +315,7 @@
 // Authorization requires spanner.databases.setIamPolicy permission on
 // [resource][google.iam.v1.SetIamPolicyRequest.resource].
 func (c *DatabaseAdminClient) SetIamPolicy(ctx context.Context, req *iampb.SetIamPolicyRequest, opts ...gax.CallOption) (*iampb.Policy, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.SetIamPolicy[0:len(c.CallOptions.SetIamPolicy):len(c.CallOptions.SetIamPolicy)], opts...)
 	var resp *iampb.Policy
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -334,7 +335,7 @@
 // Authorization requires spanner.databases.getIamPolicy permission on
 // [resource][google.iam.v1.GetIamPolicyRequest.resource].
 func (c *DatabaseAdminClient) GetIamPolicy(ctx context.Context, req *iampb.GetIamPolicyRequest, opts ...gax.CallOption) (*iampb.Policy, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.GetIamPolicy[0:len(c.CallOptions.GetIamPolicy):len(c.CallOptions.GetIamPolicy)], opts...)
 	var resp *iampb.Policy
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -355,7 +356,7 @@
 // the containing Cloud Spanner instance. Otherwise returns an empty set of
 // permissions.
 func (c *DatabaseAdminClient) TestIamPermissions(ctx context.Context, req *iampb.TestIamPermissionsRequest, opts ...gax.CallOption) (*iampb.TestIamPermissionsResponse, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.TestIamPermissions[0:len(c.CallOptions.TestIamPermissions):len(c.CallOptions.TestIamPermissions)], opts...)
 	var resp *iampb.TestIamPermissionsResponse
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
diff --git a/spanner/admin/database/apiv1/doc.go b/spanner/admin/database/apiv1/doc.go
index 9c56f1e..f5f3c57 100644
--- a/spanner/admin/database/apiv1/doc.go
+++ b/spanner/admin/database/apiv1/doc.go
@@ -14,9 +14,11 @@
 
 // AUTO-GENERATED CODE. DO NOT EDIT.
 
-// Package database is an experimental, auto-generated package for the
+// Package database is an auto-generated package for the
 // Cloud Spanner Database Admin API.
 //
+//   NOTE: This package is in alpha. It is not stable, and is likely to be subject to changes.
+//
 package database // import "cloud.google.com/go/spanner/admin/database/apiv1"
 
 import (
@@ -24,11 +26,15 @@
 	"google.golang.org/grpc/metadata"
 )
 
-func insertXGoog(ctx context.Context, val []string) context.Context {
-	md, _ := metadata.FromOutgoingContext(ctx)
-	md = md.Copy()
-	md["x-goog-api-client"] = val
-	return metadata.NewOutgoingContext(ctx, md)
+func insertMetadata(ctx context.Context, mds ...metadata.MD) context.Context {
+	out, _ := metadata.FromOutgoingContext(ctx)
+	out = out.Copy()
+	for _, md := range mds {
+		for k, v := range md {
+			out[k] = append(out[k], v...)
+		}
+	}
+	return metadata.NewOutgoingContext(ctx, out)
 }
 
 // DefaultAuthScopes reports the default set of authentication scopes to use with this package.
diff --git a/spanner/admin/instance/apiv1/doc.go b/spanner/admin/instance/apiv1/doc.go
index 332b695..3cf6c8f 100644
--- a/spanner/admin/instance/apiv1/doc.go
+++ b/spanner/admin/instance/apiv1/doc.go
@@ -14,9 +14,11 @@
 
 // AUTO-GENERATED CODE. DO NOT EDIT.
 
-// Package instance is an experimental, auto-generated package for the
+// Package instance is an auto-generated package for the
 // Cloud Spanner Instance Admin API.
 //
+//   NOTE: This package is in alpha. It is not stable, and is likely to be subject to changes.
+//
 package instance // import "cloud.google.com/go/spanner/admin/instance/apiv1"
 
 import (
@@ -24,11 +26,15 @@
 	"google.golang.org/grpc/metadata"
 )
 
-func insertXGoog(ctx context.Context, val []string) context.Context {
-	md, _ := metadata.FromOutgoingContext(ctx)
-	md = md.Copy()
-	md["x-goog-api-client"] = val
-	return metadata.NewOutgoingContext(ctx, md)
+func insertMetadata(ctx context.Context, mds ...metadata.MD) context.Context {
+	out, _ := metadata.FromOutgoingContext(ctx)
+	out = out.Copy()
+	for _, md := range mds {
+		for k, v := range md {
+			out[k] = append(out[k], v...)
+		}
+	}
+	return metadata.NewOutgoingContext(ctx, out)
 }
 
 // DefaultAuthScopes reports the default set of authentication scopes to use with this package.
diff --git a/spanner/admin/instance/apiv1/instance_admin_client.go b/spanner/admin/instance/apiv1/instance_admin_client.go
index 125fc35..6c7392c 100644
--- a/spanner/admin/instance/apiv1/instance_admin_client.go
+++ b/spanner/admin/instance/apiv1/instance_admin_client.go
@@ -33,6 +33,7 @@
 	instancepb "google.golang.org/genproto/googleapis/spanner/admin/instance/v1"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/metadata"
 )
 
 // InstanceAdminCallOptions contains the retry settings for each method of InstanceAdminClient.
@@ -102,7 +103,7 @@
 	CallOptions *InstanceAdminCallOptions
 
 	// The metadata to be sent with each request.
-	xGoogHeader []string
+	Metadata metadata.MD
 }
 
 // NewInstanceAdminClient creates a new instance admin client.
@@ -171,7 +172,7 @@
 func (c *InstanceAdminClient) setGoogleClientInfo(keyval ...string) {
 	kv := append([]string{"gl-go", version.Go()}, keyval...)
 	kv = append(kv, "gapic", version.Repo, "gax", gax.Version, "grpc", grpc.Version)
-	c.xGoogHeader = []string{gax.XGoogHeader(kv...)}
+	c.Metadata = metadata.Pairs("x-goog-api-client", gax.XGoogHeader(kv...))
 }
 
 // InstanceAdminProjectPath returns the path for the project resource.
@@ -204,7 +205,7 @@
 
 // ListInstanceConfigs lists the supported instance configurations for a given project.
 func (c *InstanceAdminClient) ListInstanceConfigs(ctx context.Context, req *instancepb.ListInstanceConfigsRequest, opts ...gax.CallOption) *InstanceConfigIterator {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.ListInstanceConfigs[0:len(c.CallOptions.ListInstanceConfigs):len(c.CallOptions.ListInstanceConfigs)], opts...)
 	it := &InstanceConfigIterator{}
 	it.InternalFetch = func(pageSize int, pageToken string) ([]*instancepb.InstanceConfig, string, error) {
@@ -239,7 +240,7 @@
 
 // GetInstanceConfig gets information about a particular instance configuration.
 func (c *InstanceAdminClient) GetInstanceConfig(ctx context.Context, req *instancepb.GetInstanceConfigRequest, opts ...gax.CallOption) (*instancepb.InstanceConfig, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.GetInstanceConfig[0:len(c.CallOptions.GetInstanceConfig):len(c.CallOptions.GetInstanceConfig)], opts...)
 	var resp *instancepb.InstanceConfig
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -255,7 +256,7 @@
 
 // ListInstances lists all instances in the given project.
 func (c *InstanceAdminClient) ListInstances(ctx context.Context, req *instancepb.ListInstancesRequest, opts ...gax.CallOption) *InstanceIterator {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.ListInstances[0:len(c.CallOptions.ListInstances):len(c.CallOptions.ListInstances)], opts...)
 	it := &InstanceIterator{}
 	it.InternalFetch = func(pageSize int, pageToken string) ([]*instancepb.Instance, string, error) {
@@ -290,7 +291,7 @@
 
 // GetInstance gets information about a particular instance.
 func (c *InstanceAdminClient) GetInstance(ctx context.Context, req *instancepb.GetInstanceRequest, opts ...gax.CallOption) (*instancepb.Instance, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.GetInstance[0:len(c.CallOptions.GetInstance):len(c.CallOptions.GetInstance)], opts...)
 	var resp *instancepb.Instance
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -344,7 +345,7 @@
 // The [response][google.longrunning.Operation.response] field type is
 // [Instance][google.spanner.admin.instance.v1.Instance], if successful.
 func (c *InstanceAdminClient) CreateInstance(ctx context.Context, req *instancepb.CreateInstanceRequest, opts ...gax.CallOption) (*CreateInstanceOperation, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.CreateInstance[0:len(c.CallOptions.CreateInstance):len(c.CallOptions.CreateInstance)], opts...)
 	var resp *longrunningpb.Operation
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -405,7 +406,7 @@
 // Authorization requires spanner.instances.update permission on
 // resource [name][google.spanner.admin.instance.v1.Instance.name].
 func (c *InstanceAdminClient) UpdateInstance(ctx context.Context, req *instancepb.UpdateInstanceRequest, opts ...gax.CallOption) (*UpdateInstanceOperation, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.UpdateInstance[0:len(c.CallOptions.UpdateInstance):len(c.CallOptions.UpdateInstance)], opts...)
 	var resp *longrunningpb.Operation
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -433,7 +434,7 @@
 //   irrevocably disappear from the API. All data in the databases
 //   is permanently deleted.
 func (c *InstanceAdminClient) DeleteInstance(ctx context.Context, req *instancepb.DeleteInstanceRequest, opts ...gax.CallOption) error {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.DeleteInstance[0:len(c.CallOptions.DeleteInstance):len(c.CallOptions.DeleteInstance)], opts...)
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
 		var err error
@@ -449,7 +450,7 @@
 // Authorization requires spanner.instances.setIamPolicy on
 // [resource][google.iam.v1.SetIamPolicyRequest.resource].
 func (c *InstanceAdminClient) SetIamPolicy(ctx context.Context, req *iampb.SetIamPolicyRequest, opts ...gax.CallOption) (*iampb.Policy, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.SetIamPolicy[0:len(c.CallOptions.SetIamPolicy):len(c.CallOptions.SetIamPolicy)], opts...)
 	var resp *iampb.Policy
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -469,7 +470,7 @@
 // Authorization requires spanner.instances.getIamPolicy on
 // [resource][google.iam.v1.GetIamPolicyRequest.resource].
 func (c *InstanceAdminClient) GetIamPolicy(ctx context.Context, req *iampb.GetIamPolicyRequest, opts ...gax.CallOption) (*iampb.Policy, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.GetIamPolicy[0:len(c.CallOptions.GetIamPolicy):len(c.CallOptions.GetIamPolicy)], opts...)
 	var resp *iampb.Policy
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -490,7 +491,7 @@
 // permission on the containing Google Cloud Project. Otherwise returns an
 // empty set of permissions.
 func (c *InstanceAdminClient) TestIamPermissions(ctx context.Context, req *iampb.TestIamPermissionsRequest, opts ...gax.CallOption) (*iampb.TestIamPermissionsResponse, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.TestIamPermissions[0:len(c.CallOptions.TestIamPermissions):len(c.CallOptions.TestIamPermissions)], opts...)
 	var resp *iampb.TestIamPermissionsResponse
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
diff --git a/spanner/apiv1/doc.go b/spanner/apiv1/doc.go
index d6bf754..f64f860 100644
--- a/spanner/apiv1/doc.go
+++ b/spanner/apiv1/doc.go
@@ -14,9 +14,11 @@
 
 // AUTO-GENERATED CODE. DO NOT EDIT.
 
-// Package spanner is an experimental, auto-generated package for the
+// Package spanner is an auto-generated package for the
 // Cloud Spanner API.
 //
+//   NOTE: This package is in alpha. It is not stable, and is likely to be subject to changes.
+//
 // Cloud Spanner is a managed, mission-critical, globally consistent and
 // scalable relational database service.
 //
@@ -28,11 +30,15 @@
 	"google.golang.org/grpc/metadata"
 )
 
-func insertXGoog(ctx context.Context, val []string) context.Context {
-	md, _ := metadata.FromOutgoingContext(ctx)
-	md = md.Copy()
-	md["x-goog-api-client"] = val
-	return metadata.NewOutgoingContext(ctx, md)
+func insertMetadata(ctx context.Context, mds ...metadata.MD) context.Context {
+	out, _ := metadata.FromOutgoingContext(ctx)
+	out = out.Copy()
+	for _, md := range mds {
+		for k, v := range md {
+			out[k] = append(out[k], v...)
+		}
+	}
+	return metadata.NewOutgoingContext(ctx, out)
 }
 
 // DefaultAuthScopes reports the default set of authentication scopes to use with this package.
diff --git a/spanner/apiv1/mock_test.go b/spanner/apiv1/mock_test.go
index dd8a546..bffe7f6 100644
--- a/spanner/apiv1/mock_test.go
+++ b/spanner/apiv1/mock_test.go
@@ -85,6 +85,18 @@
 	return s.resps[0].(*spannerpb.Session), nil
 }
 
+func (s *mockSpannerServer) ListSessions(ctx context.Context, req *spannerpb.ListSessionsRequest) (*spannerpb.ListSessionsResponse, error) {
+	md, _ := metadata.FromIncomingContext(ctx)
+	if xg := md["x-goog-api-client"]; len(xg) == 0 || !strings.Contains(xg[0], "gl-go/") {
+		return nil, fmt.Errorf("x-goog-api-client = %v, expected gl-go key", xg)
+	}
+	s.reqs = append(s.reqs, req)
+	if s.err != nil {
+		return nil, s.err
+	}
+	return s.resps[0].(*spannerpb.ListSessionsResponse), nil
+}
+
 func (s *mockSpannerServer) DeleteSession(ctx context.Context, req *spannerpb.DeleteSessionRequest) (*emptypb.Empty, error) {
 	md, _ := metadata.FromIncomingContext(ctx)
 	if xg := md["x-goog-api-client"]; len(xg) == 0 || !strings.Contains(xg[0], "gl-go/") {
@@ -338,6 +350,78 @@
 	}
 	_ = resp
 }
+func TestSpannerListSessions(t *testing.T) {
+	var nextPageToken string = ""
+	var sessionsElement *spannerpb.Session = &spannerpb.Session{}
+	var sessions = []*spannerpb.Session{sessionsElement}
+	var expectedResponse = &spannerpb.ListSessionsResponse{
+		NextPageToken: nextPageToken,
+		Sessions:      sessions,
+	}
+
+	mockSpanner.err = nil
+	mockSpanner.reqs = nil
+
+	mockSpanner.resps = append(mockSpanner.resps[:0], expectedResponse)
+
+	var formattedDatabase string = DatabasePath("[PROJECT]", "[INSTANCE]", "[DATABASE]")
+	var request = &spannerpb.ListSessionsRequest{
+		Database: formattedDatabase,
+	}
+
+	c, err := NewClient(context.Background(), clientOpt)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	resp, err := c.ListSessions(context.Background(), request).Next()
+
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if want, got := request, mockSpanner.reqs[0]; !proto.Equal(want, got) {
+		t.Errorf("wrong request %q, want %q", got, want)
+	}
+
+	want := (interface{})(expectedResponse.Sessions[0])
+	got := (interface{})(resp)
+	var ok bool
+
+	switch want := (want).(type) {
+	case proto.Message:
+		ok = proto.Equal(want, got.(proto.Message))
+	default:
+		ok = want == got
+	}
+	if !ok {
+		t.Errorf("wrong response %q, want %q)", got, want)
+	}
+}
+
+func TestSpannerListSessionsError(t *testing.T) {
+	errCode := codes.PermissionDenied
+	mockSpanner.err = gstatus.Error(errCode, "test error")
+
+	var formattedDatabase string = DatabasePath("[PROJECT]", "[INSTANCE]", "[DATABASE]")
+	var request = &spannerpb.ListSessionsRequest{
+		Database: formattedDatabase,
+	}
+
+	c, err := NewClient(context.Background(), clientOpt)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	resp, err := c.ListSessions(context.Background(), request).Next()
+
+	if st, ok := gstatus.FromError(err); !ok {
+		t.Errorf("got error %v, expected grpc error", err)
+	} else if c := st.Code(); c != errCode {
+		t.Errorf("got error code %q, want %q", c, errCode)
+	}
+	_ = resp
+}
 func TestSpannerDeleteSession(t *testing.T) {
 	var expectedResponse *emptypb.Empty = &emptypb.Empty{}
 
diff --git a/spanner/apiv1/spanner_client.go b/spanner/apiv1/spanner_client.go
index d20a93d..af4ce90 100644
--- a/spanner/apiv1/spanner_client.go
+++ b/spanner/apiv1/spanner_client.go
@@ -17,22 +17,26 @@
 package spanner
 
 import (
+	"math"
 	"time"
 
 	"cloud.google.com/go/internal/version"
 	gax "github.com/googleapis/gax-go"
 	"golang.org/x/net/context"
+	"google.golang.org/api/iterator"
 	"google.golang.org/api/option"
 	"google.golang.org/api/transport"
 	spannerpb "google.golang.org/genproto/googleapis/spanner/v1"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/metadata"
 )
 
 // CallOptions contains the retry settings for each method of Client.
 type CallOptions struct {
 	CreateSession       []gax.CallOption
 	GetSession          []gax.CallOption
+	ListSessions        []gax.CallOption
 	DeleteSession       []gax.CallOption
 	ExecuteSql          []gax.CallOption
 	ExecuteStreamingSql []gax.CallOption
@@ -79,6 +83,7 @@
 	return &CallOptions{
 		CreateSession:       retry[[2]string{"default", "idempotent"}],
 		GetSession:          retry[[2]string{"default", "idempotent"}],
+		ListSessions:        retry[[2]string{"default", "idempotent"}],
 		DeleteSession:       retry[[2]string{"default", "idempotent"}],
 		ExecuteSql:          retry[[2]string{"default", "idempotent"}],
 		ExecuteStreamingSql: retry[[2]string{"default", "non_idempotent"}],
@@ -102,7 +107,7 @@
 	CallOptions *CallOptions
 
 	// The metadata to be sent with each request.
-	xGoogHeader []string
+	Metadata metadata.MD
 }
 
 // NewClient creates a new spanner client.
@@ -143,7 +148,7 @@
 func (c *Client) SetGoogleClientInfo(keyval ...string) {
 	kv := append([]string{"gl-go", version.Go()}, keyval...)
 	kv = append(kv, "gapic", version.Repo, "gax", gax.Version, "grpc", grpc.Version)
-	c.xGoogHeader = []string{gax.XGoogHeader(kv...)}
+	c.Metadata = metadata.Pairs("x-goog-api-client", gax.XGoogHeader(kv...))
 }
 
 // DatabasePath returns the path for the database resource.
@@ -192,7 +197,7 @@
 // Idle sessions can be kept alive by sending a trivial SQL query
 // periodically, e.g., "SELECT 1".
 func (c *Client) CreateSession(ctx context.Context, req *spannerpb.CreateSessionRequest, opts ...gax.CallOption) (*spannerpb.Session, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.CreateSession[0:len(c.CallOptions.CreateSession):len(c.CallOptions.CreateSession)], opts...)
 	var resp *spannerpb.Session
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -210,7 +215,7 @@
 // This is mainly useful for determining whether a session is still
 // alive.
 func (c *Client) GetSession(ctx context.Context, req *spannerpb.GetSessionRequest, opts ...gax.CallOption) (*spannerpb.Session, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.GetSession[0:len(c.CallOptions.GetSession):len(c.CallOptions.GetSession)], opts...)
 	var resp *spannerpb.Session
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -224,9 +229,44 @@
 	return resp, nil
 }
 
+// ListSessions lists all sessions in a given database.
+func (c *Client) ListSessions(ctx context.Context, req *spannerpb.ListSessionsRequest, opts ...gax.CallOption) *SessionIterator {
+	ctx = insertMetadata(ctx, c.Metadata)
+	opts = append(c.CallOptions.ListSessions[0:len(c.CallOptions.ListSessions):len(c.CallOptions.ListSessions)], opts...)
+	it := &SessionIterator{}
+	it.InternalFetch = func(pageSize int, pageToken string) ([]*spannerpb.Session, string, error) {
+		var resp *spannerpb.ListSessionsResponse
+		req.PageToken = pageToken
+		if pageSize > math.MaxInt32 {
+			req.PageSize = math.MaxInt32
+		} else {
+			req.PageSize = int32(pageSize)
+		}
+		err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
+			var err error
+			resp, err = c.client.ListSessions(ctx, req, settings.GRPC...)
+			return err
+		}, opts...)
+		if err != nil {
+			return nil, "", err
+		}
+		return resp.Sessions, resp.NextPageToken, nil
+	}
+	fetch := func(pageSize int, pageToken string) (string, error) {
+		items, nextPageToken, err := it.InternalFetch(pageSize, pageToken)
+		if err != nil {
+			return "", err
+		}
+		it.items = append(it.items, items...)
+		return nextPageToken, nil
+	}
+	it.pageInfo, it.nextFunc = iterator.NewPageInfo(fetch, it.bufLen, it.takeBuf)
+	return it
+}
+
 // DeleteSession ends a session, releasing server resources associated with it.
 func (c *Client) DeleteSession(ctx context.Context, req *spannerpb.DeleteSessionRequest, opts ...gax.CallOption) error {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.DeleteSession[0:len(c.CallOptions.DeleteSession):len(c.CallOptions.DeleteSession)], opts...)
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
 		var err error
@@ -248,7 +288,7 @@
 // Larger result sets can be fetched in streaming fashion by calling
 // [ExecuteStreamingSql][google.spanner.v1.Spanner.ExecuteStreamingSql] instead.
 func (c *Client) ExecuteSql(ctx context.Context, req *spannerpb.ExecuteSqlRequest, opts ...gax.CallOption) (*spannerpb.ResultSet, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.ExecuteSql[0:len(c.CallOptions.ExecuteSql):len(c.CallOptions.ExecuteSql)], opts...)
 	var resp *spannerpb.ResultSet
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -268,7 +308,7 @@
 // individual row in the result set can exceed 100 MiB, and no
 // column value can exceed 10 MiB.
 func (c *Client) ExecuteStreamingSql(ctx context.Context, req *spannerpb.ExecuteSqlRequest, opts ...gax.CallOption) (spannerpb.Spanner_ExecuteStreamingSqlClient, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.ExecuteStreamingSql[0:len(c.CallOptions.ExecuteStreamingSql):len(c.CallOptions.ExecuteStreamingSql)], opts...)
 	var resp spannerpb.Spanner_ExecuteStreamingSqlClient
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -296,7 +336,7 @@
 // Larger result sets can be yielded in streaming fashion by calling
 // [StreamingRead][google.spanner.v1.Spanner.StreamingRead] instead.
 func (c *Client) Read(ctx context.Context, req *spannerpb.ReadRequest, opts ...gax.CallOption) (*spannerpb.ResultSet, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.Read[0:len(c.CallOptions.Read):len(c.CallOptions.Read)], opts...)
 	var resp *spannerpb.ResultSet
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -316,7 +356,7 @@
 // the result set can exceed 100 MiB, and no column value can exceed
 // 10 MiB.
 func (c *Client) StreamingRead(ctx context.Context, req *spannerpb.ReadRequest, opts ...gax.CallOption) (spannerpb.Spanner_StreamingReadClient, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.StreamingRead[0:len(c.CallOptions.StreamingRead):len(c.CallOptions.StreamingRead)], opts...)
 	var resp spannerpb.Spanner_StreamingReadClient
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -335,7 +375,7 @@
 // [Commit][google.spanner.v1.Spanner.Commit] can begin a new transaction as a
 // side-effect.
 func (c *Client) BeginTransaction(ctx context.Context, req *spannerpb.BeginTransactionRequest, opts ...gax.CallOption) (*spannerpb.Transaction, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.BeginTransaction[0:len(c.CallOptions.BeginTransaction):len(c.CallOptions.BeginTransaction)], opts...)
 	var resp *spannerpb.Transaction
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -358,7 +398,7 @@
 // reasons. If Commit returns ABORTED, the caller should re-attempt
 // the transaction from the beginning, re-using the same session.
 func (c *Client) Commit(ctx context.Context, req *spannerpb.CommitRequest, opts ...gax.CallOption) (*spannerpb.CommitResponse, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.Commit[0:len(c.CallOptions.Commit):len(c.CallOptions.Commit)], opts...)
 	var resp *spannerpb.CommitResponse
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -381,7 +421,7 @@
 // transaction was already aborted, or the transaction is not
 // found. Rollback never returns ABORTED.
 func (c *Client) Rollback(ctx context.Context, req *spannerpb.RollbackRequest, opts ...gax.CallOption) error {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.Rollback[0:len(c.CallOptions.Rollback):len(c.CallOptions.Rollback)], opts...)
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
 		var err error
@@ -390,3 +430,45 @@
 	}, opts...)
 	return err
 }
+
+// SessionIterator manages a stream of *spannerpb.Session.
+type SessionIterator struct {
+	items    []*spannerpb.Session
+	pageInfo *iterator.PageInfo
+	nextFunc func() error
+
+	// InternalFetch is for use by the Google Cloud Libraries only.
+	// It is not part of the stable interface of this package.
+	//
+	// InternalFetch returns results from a single call to the underlying RPC.
+	// The number of results is no greater than pageSize.
+	// If there are no more results, nextPageToken is empty and err is nil.
+	InternalFetch func(pageSize int, pageToken string) (results []*spannerpb.Session, nextPageToken string, err error)
+}
+
+// PageInfo supports pagination. See the google.golang.org/api/iterator package for details.
+func (it *SessionIterator) PageInfo() *iterator.PageInfo {
+	return it.pageInfo
+}
+
+// Next returns the next result. Its second return value is iterator.Done if there are no more
+// results. Once Next returns Done, all subsequent calls will return Done.
+func (it *SessionIterator) Next() (*spannerpb.Session, error) {
+	var item *spannerpb.Session
+	if err := it.nextFunc(); err != nil {
+		return item, err
+	}
+	item = it.items[0]
+	it.items = it.items[1:]
+	return item, nil
+}
+
+func (it *SessionIterator) bufLen() int {
+	return len(it.items)
+}
+
+func (it *SessionIterator) takeBuf() interface{} {
+	b := it.items
+	it.items = nil
+	return b
+}
diff --git a/spanner/apiv1/spanner_client_example_test.go b/spanner/apiv1/spanner_client_example_test.go
index 55ee8d1..e763305 100644
--- a/spanner/apiv1/spanner_client_example_test.go
+++ b/spanner/apiv1/spanner_client_example_test.go
@@ -21,6 +21,7 @@
 
 	"cloud.google.com/go/spanner/apiv1"
 	"golang.org/x/net/context"
+	"google.golang.org/api/iterator"
 	spannerpb "google.golang.org/genproto/googleapis/spanner/v1"
 )
 
@@ -70,6 +71,30 @@
 	_ = resp
 }
 
+func ExampleClient_ListSessions() {
+	ctx := context.Background()
+	c, err := spanner.NewClient(ctx)
+	if err != nil {
+		// TODO: Handle error.
+	}
+
+	req := &spannerpb.ListSessionsRequest{
+	// TODO: Fill request struct fields.
+	}
+	it := c.ListSessions(ctx, req)
+	for {
+		resp, err := it.Next()
+		if err == iterator.Done {
+			break
+		}
+		if err != nil {
+			// TODO: Handle error.
+		}
+		// TODO: Use resp.
+		_ = resp
+	}
+}
+
 func ExampleClient_DeleteSession() {
 	ctx := context.Background()
 	c, err := spanner.NewClient(ctx)
diff --git a/speech/apiv1/doc.go b/speech/apiv1/doc.go
index ceea385..c5ea0e8 100644
--- a/speech/apiv1/doc.go
+++ b/speech/apiv1/doc.go
@@ -16,6 +16,7 @@
 
 // Package speech is an auto-generated package for the
 // Google Cloud Speech API.
+
 //
 // Google Cloud Speech API.
 package speech // import "cloud.google.com/go/speech/apiv1"
@@ -25,11 +26,15 @@
 	"google.golang.org/grpc/metadata"
 )
 
-func insertXGoog(ctx context.Context, val []string) context.Context {
-	md, _ := metadata.FromOutgoingContext(ctx)
-	md = md.Copy()
-	md["x-goog-api-client"] = val
-	return metadata.NewOutgoingContext(ctx, md)
+func insertMetadata(ctx context.Context, mds ...metadata.MD) context.Context {
+	out, _ := metadata.FromOutgoingContext(ctx)
+	out = out.Copy()
+	for _, md := range mds {
+		for k, v := range md {
+			out[k] = append(out[k], v...)
+		}
+	}
+	return metadata.NewOutgoingContext(ctx, out)
 }
 
 // DefaultAuthScopes reports the default set of authentication scopes to use with this package.
diff --git a/speech/apiv1/speech_client.go b/speech/apiv1/speech_client.go
index 0f618ef..cbedcf7 100644
--- a/speech/apiv1/speech_client.go
+++ b/speech/apiv1/speech_client.go
@@ -30,6 +30,7 @@
 	longrunningpb "google.golang.org/genproto/googleapis/longrunning"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/metadata"
 )
 
 // CallOptions contains the retry settings for each method of Client.
@@ -85,7 +86,7 @@
 	CallOptions *CallOptions
 
 	// The metadata to be sent with each request.
-	xGoogHeader []string
+	Metadata metadata.MD
 }
 
 // NewClient creates a new speech client.
@@ -134,13 +135,13 @@
 func (c *Client) setGoogleClientInfo(keyval ...string) {
 	kv := append([]string{"gl-go", version.Go()}, keyval...)
 	kv = append(kv, "gapic", version.Repo, "gax", gax.Version, "grpc", grpc.Version)
-	c.xGoogHeader = []string{gax.XGoogHeader(kv...)}
+	c.Metadata = metadata.Pairs("x-goog-api-client", gax.XGoogHeader(kv...))
 }
 
 // Recognize performs synchronous speech recognition: receive results after all audio
 // has been sent and processed.
 func (c *Client) Recognize(ctx context.Context, req *speechpb.RecognizeRequest, opts ...gax.CallOption) (*speechpb.RecognizeResponse, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.Recognize[0:len(c.CallOptions.Recognize):len(c.CallOptions.Recognize)], opts...)
 	var resp *speechpb.RecognizeResponse
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -159,7 +160,7 @@
 // Operation.error or an Operation.response which contains
 // a LongRunningRecognizeResponse message.
 func (c *Client) LongRunningRecognize(ctx context.Context, req *speechpb.LongRunningRecognizeRequest, opts ...gax.CallOption) (*LongRunningRecognizeOperation, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.LongRunningRecognize[0:len(c.CallOptions.LongRunningRecognize):len(c.CallOptions.LongRunningRecognize)], opts...)
 	var resp *longrunningpb.Operation
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -178,7 +179,7 @@
 // StreamingRecognize performs bidirectional streaming speech recognition: receive results while
 // sending audio. This method is only available via the gRPC API (not REST).
 func (c *Client) StreamingRecognize(ctx context.Context, opts ...gax.CallOption) (speechpb.Speech_StreamingRecognizeClient, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.StreamingRecognize[0:len(c.CallOptions.StreamingRecognize):len(c.CallOptions.StreamingRecognize)], opts...)
 	var resp speechpb.Speech_StreamingRecognizeClient
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
diff --git a/speech/apiv1beta1/doc.go b/speech/apiv1beta1/doc.go
index 83ba265..fbc9b94 100644
--- a/speech/apiv1beta1/doc.go
+++ b/speech/apiv1beta1/doc.go
@@ -14,9 +14,11 @@
 
 // AUTO-GENERATED CODE. DO NOT EDIT.
 
-// Package speech is an experimental, auto-generated package for the
+// Package speech is an auto-generated package for the
 // Google Cloud Speech API.
 //
+//   NOTE: This package is in alpha. It is not stable, and is likely to be subject to changes.
+//
 // Google Cloud Speech API.
 package speech // import "cloud.google.com/go/speech/apiv1beta1"
 
@@ -25,11 +27,15 @@
 	"google.golang.org/grpc/metadata"
 )
 
-func insertXGoog(ctx context.Context, val []string) context.Context {
-	md, _ := metadata.FromOutgoingContext(ctx)
-	md = md.Copy()
-	md["x-goog-api-client"] = val
-	return metadata.NewOutgoingContext(ctx, md)
+func insertMetadata(ctx context.Context, mds ...metadata.MD) context.Context {
+	out, _ := metadata.FromOutgoingContext(ctx)
+	out = out.Copy()
+	for _, md := range mds {
+		for k, v := range md {
+			out[k] = append(out[k], v...)
+		}
+	}
+	return metadata.NewOutgoingContext(ctx, out)
 }
 
 // DefaultAuthScopes reports the default set of authentication scopes to use with this package.
diff --git a/speech/apiv1beta1/speech_client.go b/speech/apiv1beta1/speech_client.go
index d5e7603..3e2ecbb 100644
--- a/speech/apiv1beta1/speech_client.go
+++ b/speech/apiv1beta1/speech_client.go
@@ -30,6 +30,7 @@
 	longrunningpb "google.golang.org/genproto/googleapis/longrunning"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/metadata"
 )
 
 // CallOptions contains the retry settings for each method of Client.
@@ -85,7 +86,7 @@
 	CallOptions *CallOptions
 
 	// The metadata to be sent with each request.
-	xGoogHeader []string
+	Metadata metadata.MD
 }
 
 // NewClient creates a new speech client.
@@ -134,13 +135,13 @@
 func (c *Client) setGoogleClientInfo(keyval ...string) {
 	kv := append([]string{"gl-go", version.Go()}, keyval...)
 	kv = append(kv, "gapic", version.Repo, "gax", gax.Version, "grpc", grpc.Version)
-	c.xGoogHeader = []string{gax.XGoogHeader(kv...)}
+	c.Metadata = metadata.Pairs("x-goog-api-client", gax.XGoogHeader(kv...))
 }
 
 // SyncRecognize performs synchronous speech recognition: receive results after all audio
 // has been sent and processed.
 func (c *Client) SyncRecognize(ctx context.Context, req *speechpb.SyncRecognizeRequest, opts ...gax.CallOption) (*speechpb.SyncRecognizeResponse, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.SyncRecognize[0:len(c.CallOptions.SyncRecognize):len(c.CallOptions.SyncRecognize)], opts...)
 	var resp *speechpb.SyncRecognizeResponse
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -161,7 +162,7 @@
 // Operation.error or an Operation.response which contains
 // an AsyncRecognizeResponse message.
 func (c *Client) AsyncRecognize(ctx context.Context, req *speechpb.AsyncRecognizeRequest, opts ...gax.CallOption) (*AsyncRecognizeOperation, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.AsyncRecognize[0:len(c.CallOptions.AsyncRecognize):len(c.CallOptions.AsyncRecognize)], opts...)
 	var resp *longrunningpb.Operation
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
@@ -180,7 +181,7 @@
 // StreamingRecognize performs bidirectional streaming speech recognition: receive results while
 // sending audio. This method is only available via the gRPC API (not REST).
 func (c *Client) StreamingRecognize(ctx context.Context, opts ...gax.CallOption) (speechpb.Speech_StreamingRecognizeClient, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.StreamingRecognize[0:len(c.CallOptions.StreamingRecognize):len(c.CallOptions.StreamingRecognize)], opts...)
 	var resp speechpb.Speech_StreamingRecognizeClient
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
diff --git a/trace/apiv1/doc.go b/trace/apiv1/doc.go
index 4aeb779..4d904c5 100644
--- a/trace/apiv1/doc.go
+++ b/trace/apiv1/doc.go
@@ -14,15 +14,16 @@
 
 // AUTO-GENERATED CODE. DO NOT EDIT.
 
-// Package trace is an experimental, auto-generated package for the
+// Package trace is an auto-generated package for the
 // Stackdriver Trace API.
 //
+//   NOTE: This package is in alpha. It is not stable, and is likely to be subject to changes.
+//
 // Send and retrieve trace data from Stackdriver Trace. Data is generated and
 // available by default for all App Engine applications. Data from other
 // applications can be written to Stackdriver Trace for display, reporting,
-// and analysis.
-//
-// Use the client at cloud.google.com/go/trace in preference to this.
+// and
+// analysis.
 package trace // import "cloud.google.com/go/trace/apiv1"
 
 import (
@@ -30,11 +31,15 @@
 	"google.golang.org/grpc/metadata"
 )
 
-func insertXGoog(ctx context.Context, val []string) context.Context {
-	md, _ := metadata.FromOutgoingContext(ctx)
-	md = md.Copy()
-	md["x-goog-api-client"] = val
-	return metadata.NewOutgoingContext(ctx, md)
+func insertMetadata(ctx context.Context, mds ...metadata.MD) context.Context {
+	out, _ := metadata.FromOutgoingContext(ctx)
+	out = out.Copy()
+	for _, md := range mds {
+		for k, v := range md {
+			out[k] = append(out[k], v...)
+		}
+	}
+	return metadata.NewOutgoingContext(ctx, out)
 }
 
 // DefaultAuthScopes reports the default set of authentication scopes to use with this package.
diff --git a/trace/apiv1/mock_test.go b/trace/apiv1/mock_test.go
index c69283b..d1b617b 100644
--- a/trace/apiv1/mock_test.go
+++ b/trace/apiv1/mock_test.go
@@ -126,127 +126,6 @@
 	os.Exit(m.Run())
 }
 
-func TestTraceServicePatchTraces(t *testing.T) {
-	var expectedResponse *emptypb.Empty = &emptypb.Empty{}
-
-	mockTrace.err = nil
-	mockTrace.reqs = nil
-
-	mockTrace.resps = append(mockTrace.resps[:0], expectedResponse)
-
-	var projectId string = "projectId-1969970175"
-	var traces *cloudtracepb.Traces = &cloudtracepb.Traces{}
-	var request = &cloudtracepb.PatchTracesRequest{
-		ProjectId: projectId,
-		Traces:    traces,
-	}
-
-	c, err := NewClient(context.Background(), clientOpt)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	err = c.PatchTraces(context.Background(), request)
-
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	if want, got := request, mockTrace.reqs[0]; !proto.Equal(want, got) {
-		t.Errorf("wrong request %q, want %q", got, want)
-	}
-
-}
-
-func TestTraceServicePatchTracesError(t *testing.T) {
-	errCode := codes.PermissionDenied
-	mockTrace.err = gstatus.Error(errCode, "test error")
-
-	var projectId string = "projectId-1969970175"
-	var traces *cloudtracepb.Traces = &cloudtracepb.Traces{}
-	var request = &cloudtracepb.PatchTracesRequest{
-		ProjectId: projectId,
-		Traces:    traces,
-	}
-
-	c, err := NewClient(context.Background(), clientOpt)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	err = c.PatchTraces(context.Background(), request)
-
-	if st, ok := gstatus.FromError(err); !ok {
-		t.Errorf("got error %v, expected grpc error", err)
-	} else if c := st.Code(); c != errCode {
-		t.Errorf("got error code %q, want %q", c, errCode)
-	}
-}
-func TestTraceServiceGetTrace(t *testing.T) {
-	var projectId2 string = "projectId2939242356"
-	var traceId2 string = "traceId2987826376"
-	var expectedResponse = &cloudtracepb.Trace{
-		ProjectId: projectId2,
-		TraceId:   traceId2,
-	}
-
-	mockTrace.err = nil
-	mockTrace.reqs = nil
-
-	mockTrace.resps = append(mockTrace.resps[:0], expectedResponse)
-
-	var projectId string = "projectId-1969970175"
-	var traceId string = "traceId1270300245"
-	var request = &cloudtracepb.GetTraceRequest{
-		ProjectId: projectId,
-		TraceId:   traceId,
-	}
-
-	c, err := NewClient(context.Background(), clientOpt)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	resp, err := c.GetTrace(context.Background(), request)
-
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	if want, got := request, mockTrace.reqs[0]; !proto.Equal(want, got) {
-		t.Errorf("wrong request %q, want %q", got, want)
-	}
-
-	if want, got := expectedResponse, resp; !proto.Equal(want, got) {
-		t.Errorf("wrong response %q, want %q)", got, want)
-	}
-}
-
-func TestTraceServiceGetTraceError(t *testing.T) {
-	errCode := codes.PermissionDenied
-	mockTrace.err = gstatus.Error(errCode, "test error")
-
-	var projectId string = "projectId-1969970175"
-	var traceId string = "traceId1270300245"
-	var request = &cloudtracepb.GetTraceRequest{
-		ProjectId: projectId,
-		TraceId:   traceId,
-	}
-
-	c, err := NewClient(context.Background(), clientOpt)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	resp, err := c.GetTrace(context.Background(), request)
-
-	if st, ok := gstatus.FromError(err); !ok {
-		t.Errorf("got error %v, expected grpc error", err)
-	} else if c := st.Code(); c != errCode {
-		t.Errorf("got error code %q, want %q", c, errCode)
-	}
-	_ = resp
-}
 func TestTraceServiceListTraces(t *testing.T) {
 	var nextPageToken string = ""
 	var tracesElement *cloudtracepb.Trace = &cloudtracepb.Trace{}
@@ -319,3 +198,124 @@
 	}
 	_ = resp
 }
+func TestTraceServiceGetTrace(t *testing.T) {
+	var projectId2 string = "projectId2939242356"
+	var traceId2 string = "traceId2987826376"
+	var expectedResponse = &cloudtracepb.Trace{
+		ProjectId: projectId2,
+		TraceId:   traceId2,
+	}
+
+	mockTrace.err = nil
+	mockTrace.reqs = nil
+
+	mockTrace.resps = append(mockTrace.resps[:0], expectedResponse)
+
+	var projectId string = "projectId-1969970175"
+	var traceId string = "traceId1270300245"
+	var request = &cloudtracepb.GetTraceRequest{
+		ProjectId: projectId,
+		TraceId:   traceId,
+	}
+
+	c, err := NewClient(context.Background(), clientOpt)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	resp, err := c.GetTrace(context.Background(), request)
+
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if want, got := request, mockTrace.reqs[0]; !proto.Equal(want, got) {
+		t.Errorf("wrong request %q, want %q", got, want)
+	}
+
+	if want, got := expectedResponse, resp; !proto.Equal(want, got) {
+		t.Errorf("wrong response %q, want %q)", got, want)
+	}
+}
+
+func TestTraceServiceGetTraceError(t *testing.T) {
+	errCode := codes.PermissionDenied
+	mockTrace.err = gstatus.Error(errCode, "test error")
+
+	var projectId string = "projectId-1969970175"
+	var traceId string = "traceId1270300245"
+	var request = &cloudtracepb.GetTraceRequest{
+		ProjectId: projectId,
+		TraceId:   traceId,
+	}
+
+	c, err := NewClient(context.Background(), clientOpt)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	resp, err := c.GetTrace(context.Background(), request)
+
+	if st, ok := gstatus.FromError(err); !ok {
+		t.Errorf("got error %v, expected grpc error", err)
+	} else if c := st.Code(); c != errCode {
+		t.Errorf("got error code %q, want %q", c, errCode)
+	}
+	_ = resp
+}
+func TestTraceServicePatchTraces(t *testing.T) {
+	var expectedResponse *emptypb.Empty = &emptypb.Empty{}
+
+	mockTrace.err = nil
+	mockTrace.reqs = nil
+
+	mockTrace.resps = append(mockTrace.resps[:0], expectedResponse)
+
+	var projectId string = "projectId-1969970175"
+	var traces *cloudtracepb.Traces = &cloudtracepb.Traces{}
+	var request = &cloudtracepb.PatchTracesRequest{
+		ProjectId: projectId,
+		Traces:    traces,
+	}
+
+	c, err := NewClient(context.Background(), clientOpt)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	err = c.PatchTraces(context.Background(), request)
+
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if want, got := request, mockTrace.reqs[0]; !proto.Equal(want, got) {
+		t.Errorf("wrong request %q, want %q", got, want)
+	}
+
+}
+
+func TestTraceServicePatchTracesError(t *testing.T) {
+	errCode := codes.PermissionDenied
+	mockTrace.err = gstatus.Error(errCode, "test error")
+
+	var projectId string = "projectId-1969970175"
+	var traces *cloudtracepb.Traces = &cloudtracepb.Traces{}
+	var request = &cloudtracepb.PatchTracesRequest{
+		ProjectId: projectId,
+		Traces:    traces,
+	}
+
+	c, err := NewClient(context.Background(), clientOpt)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	err = c.PatchTraces(context.Background(), request)
+
+	if st, ok := gstatus.FromError(err); !ok {
+		t.Errorf("got error %v, expected grpc error", err)
+	} else if c := st.Code(); c != errCode {
+		t.Errorf("got error code %q, want %q", c, errCode)
+	}
+}
diff --git a/trace/apiv1/trace_client.go b/trace/apiv1/trace_client.go
index 7560c16..e0c4964 100644
--- a/trace/apiv1/trace_client.go
+++ b/trace/apiv1/trace_client.go
@@ -29,13 +29,14 @@
 	cloudtracepb "google.golang.org/genproto/googleapis/devtools/cloudtrace/v1"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/metadata"
 )
 
 // CallOptions contains the retry settings for each method of Client.
 type CallOptions struct {
-	PatchTraces []gax.CallOption
-	GetTrace    []gax.CallOption
 	ListTraces  []gax.CallOption
+	GetTrace    []gax.CallOption
+	PatchTraces []gax.CallOption
 }
 
 func defaultClientOptions() []option.ClientOption {
@@ -61,9 +62,9 @@
 		},
 	}
 	return &CallOptions{
-		PatchTraces: retry[[2]string{"default", "idempotent"}],
-		GetTrace:    retry[[2]string{"default", "idempotent"}],
 		ListTraces:  retry[[2]string{"default", "idempotent"}],
+		GetTrace:    retry[[2]string{"default", "idempotent"}],
+		PatchTraces: retry[[2]string{"write_sink", "non_idempotent"}],
 	}
 }
 
@@ -79,7 +80,7 @@
 	CallOptions *CallOptions
 
 	// The metadata to be sent with each request.
-	xGoogHeader []string
+	Metadata metadata.MD
 }
 
 // NewClient creates a new trace service client.
@@ -100,7 +101,7 @@
 
 		client: cloudtracepb.NewTraceServiceClient(conn),
 	}
-	c.SetGoogleClientInfo()
+	c.setGoogleClientInfo()
 	return c, nil
 }
 
@@ -115,50 +116,18 @@
 	return c.conn.Close()
 }
 
-// SetGoogleClientInfo sets the name and version of the application in
+// setGoogleClientInfo sets the name and version of the application in
 // the `x-goog-api-client` header passed on each request. Intended for
 // use by Google-written clients.
-func (c *Client) SetGoogleClientInfo(keyval ...string) {
+func (c *Client) setGoogleClientInfo(keyval ...string) {
 	kv := append([]string{"gl-go", version.Go()}, keyval...)
 	kv = append(kv, "gapic", version.Repo, "gax", gax.Version, "grpc", grpc.Version)
-	c.xGoogHeader = []string{gax.XGoogHeader(kv...)}
-}
-
-// PatchTraces sends new traces to Stackdriver Trace or updates existing traces. If the ID
-// of a trace that you send matches that of an existing trace, any fields
-// in the existing trace and its spans are overwritten by the provided values,
-// and any new fields provided are merged with the existing trace data. If the
-// ID does not match, a new trace is created.
-func (c *Client) PatchTraces(ctx context.Context, req *cloudtracepb.PatchTracesRequest, opts ...gax.CallOption) error {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
-	opts = append(c.CallOptions.PatchTraces[0:len(c.CallOptions.PatchTraces):len(c.CallOptions.PatchTraces)], opts...)
-	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
-		var err error
-		_, err = c.client.PatchTraces(ctx, req, settings.GRPC...)
-		return err
-	}, opts...)
-	return err
-}
-
-// GetTrace gets a single trace by its ID.
-func (c *Client) GetTrace(ctx context.Context, req *cloudtracepb.GetTraceRequest, opts ...gax.CallOption) (*cloudtracepb.Trace, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
-	opts = append(c.CallOptions.GetTrace[0:len(c.CallOptions.GetTrace):len(c.CallOptions.GetTrace)], opts...)
-	var resp *cloudtracepb.Trace
-	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
-		var err error
-		resp, err = c.client.GetTrace(ctx, req, settings.GRPC...)
-		return err
-	}, opts...)
-	if err != nil {
-		return nil, err
-	}
-	return resp, nil
+	c.Metadata = metadata.Pairs("x-goog-api-client", gax.XGoogHeader(kv...))
 }
 
 // ListTraces returns of a list of traces that match the specified filter conditions.
 func (c *Client) ListTraces(ctx context.Context, req *cloudtracepb.ListTracesRequest, opts ...gax.CallOption) *TraceIterator {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.ListTraces[0:len(c.CallOptions.ListTraces):len(c.CallOptions.ListTraces)], opts...)
 	it := &TraceIterator{}
 	it.InternalFetch = func(pageSize int, pageToken string) ([]*cloudtracepb.Trace, string, error) {
@@ -191,6 +160,38 @@
 	return it
 }
 
+// GetTrace gets a single trace by its ID.
+func (c *Client) GetTrace(ctx context.Context, req *cloudtracepb.GetTraceRequest, opts ...gax.CallOption) (*cloudtracepb.Trace, error) {
+	ctx = insertMetadata(ctx, c.Metadata)
+	opts = append(c.CallOptions.GetTrace[0:len(c.CallOptions.GetTrace):len(c.CallOptions.GetTrace)], opts...)
+	var resp *cloudtracepb.Trace
+	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
+		var err error
+		resp, err = c.client.GetTrace(ctx, req, settings.GRPC...)
+		return err
+	}, opts...)
+	if err != nil {
+		return nil, err
+	}
+	return resp, nil
+}
+
+// PatchTraces sends new traces to Stackdriver Trace or updates existing traces. If the ID
+// of a trace that you send matches that of an existing trace, any fields
+// in the existing trace and its spans are overwritten by the provided values,
+// and any new fields provided are merged with the existing trace data. If the
+// ID does not match, a new trace is created.
+func (c *Client) PatchTraces(ctx context.Context, req *cloudtracepb.PatchTracesRequest, opts ...gax.CallOption) error {
+	ctx = insertMetadata(ctx, c.Metadata)
+	opts = append(c.CallOptions.PatchTraces[0:len(c.CallOptions.PatchTraces):len(c.CallOptions.PatchTraces)], opts...)
+	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
+		var err error
+		_, err = c.client.PatchTraces(ctx, req, settings.GRPC...)
+		return err
+	}, opts...)
+	return err
+}
+
 // TraceIterator manages a stream of *cloudtracepb.Trace.
 type TraceIterator struct {
 	items    []*cloudtracepb.Trace
diff --git a/trace/apiv1/trace_client_example_test.go b/trace/apiv1/trace_client_example_test.go
index ee885a7..f7cf91c 100644
--- a/trace/apiv1/trace_client_example_test.go
+++ b/trace/apiv1/trace_client_example_test.go
@@ -33,40 +33,6 @@
 	_ = c
 }
 
-func ExampleClient_PatchTraces() {
-	ctx := context.Background()
-	c, err := trace.NewClient(ctx)
-	if err != nil {
-		// TODO: Handle error.
-	}
-
-	req := &cloudtracepb.PatchTracesRequest{
-	// TODO: Fill request struct fields.
-	}
-	err = c.PatchTraces(ctx, req)
-	if err != nil {
-		// TODO: Handle error.
-	}
-}
-
-func ExampleClient_GetTrace() {
-	ctx := context.Background()
-	c, err := trace.NewClient(ctx)
-	if err != nil {
-		// TODO: Handle error.
-	}
-
-	req := &cloudtracepb.GetTraceRequest{
-	// TODO: Fill request struct fields.
-	}
-	resp, err := c.GetTrace(ctx, req)
-	if err != nil {
-		// TODO: Handle error.
-	}
-	// TODO: Use resp.
-	_ = resp
-}
-
 func ExampleClient_ListTraces() {
 	ctx := context.Background()
 	c, err := trace.NewClient(ctx)
@@ -90,3 +56,37 @@
 		_ = resp
 	}
 }
+
+func ExampleClient_GetTrace() {
+	ctx := context.Background()
+	c, err := trace.NewClient(ctx)
+	if err != nil {
+		// TODO: Handle error.
+	}
+
+	req := &cloudtracepb.GetTraceRequest{
+	// TODO: Fill request struct fields.
+	}
+	resp, err := c.GetTrace(ctx, req)
+	if err != nil {
+		// TODO: Handle error.
+	}
+	// TODO: Use resp.
+	_ = resp
+}
+
+func ExampleClient_PatchTraces() {
+	ctx := context.Background()
+	c, err := trace.NewClient(ctx)
+	if err != nil {
+		// TODO: Handle error.
+	}
+
+	req := &cloudtracepb.PatchTracesRequest{
+	// TODO: Fill request struct fields.
+	}
+	err = c.PatchTraces(ctx, req)
+	if err != nil {
+		// TODO: Handle error.
+	}
+}
diff --git a/videointelligence/apiv1beta1/doc.go b/videointelligence/apiv1beta1/doc.go
index 726458f..b53355e 100644
--- a/videointelligence/apiv1beta1/doc.go
+++ b/videointelligence/apiv1beta1/doc.go
@@ -14,9 +14,11 @@
 
 // AUTO-GENERATED CODE. DO NOT EDIT.
 
-// Package videointelligence is an experimental, auto-generated package for the
+// Package videointelligence is an auto-generated package for the
 // Google Cloud Video Intelligence API.
 //
+//   NOTE: This package is in alpha. It is not stable, and is likely to be subject to changes.
+//
 // Google Cloud Video Intelligence API.
 package videointelligence // import "cloud.google.com/go/videointelligence/apiv1beta1"
 
@@ -25,11 +27,15 @@
 	"google.golang.org/grpc/metadata"
 )
 
-func insertXGoog(ctx context.Context, val []string) context.Context {
-	md, _ := metadata.FromOutgoingContext(ctx)
-	md = md.Copy()
-	md["x-goog-api-client"] = val
-	return metadata.NewOutgoingContext(ctx, md)
+func insertMetadata(ctx context.Context, mds ...metadata.MD) context.Context {
+	out, _ := metadata.FromOutgoingContext(ctx)
+	out = out.Copy()
+	for _, md := range mds {
+		for k, v := range md {
+			out[k] = append(out[k], v...)
+		}
+	}
+	return metadata.NewOutgoingContext(ctx, out)
 }
 
 // DefaultAuthScopes reports the default set of authentication scopes to use with this package.
diff --git a/videointelligence/apiv1beta1/mock_test.go b/videointelligence/apiv1beta1/mock_test.go
index 7615da5..7f1c8be 100644
--- a/videointelligence/apiv1beta1/mock_test.go
+++ b/videointelligence/apiv1beta1/mock_test.go
@@ -118,8 +118,9 @@
 		Result: &longrunningpb.Operation_Response{Response: any},
 	})
 
-	var inputUri string = "inputUri1707300727"
-	var features []videointelligencepb.Feature = nil
+	var inputUri string = "gs://demomaker/cat.mp4"
+	var featuresElement videointelligencepb.Feature = videointelligencepb.Feature_LABEL_DETECTION
+	var features = []videointelligencepb.Feature{featuresElement}
 	var request = &videointelligencepb.AnnotateVideoRequest{
 		InputUri: inputUri,
 		Features: features,
@@ -163,8 +164,9 @@
 		},
 	})
 
-	var inputUri string = "inputUri1707300727"
-	var features []videointelligencepb.Feature = nil
+	var inputUri string = "gs://demomaker/cat.mp4"
+	var featuresElement videointelligencepb.Feature = videointelligencepb.Feature_LABEL_DETECTION
+	var features = []videointelligencepb.Feature{featuresElement}
 	var request = &videointelligencepb.AnnotateVideoRequest{
 		InputUri: inputUri,
 		Features: features,
diff --git a/videointelligence/apiv1beta1/video_intelligence_client.go b/videointelligence/apiv1beta1/video_intelligence_client.go
index 552e936..1001d21 100644
--- a/videointelligence/apiv1beta1/video_intelligence_client.go
+++ b/videointelligence/apiv1beta1/video_intelligence_client.go
@@ -30,6 +30,7 @@
 	longrunningpb "google.golang.org/genproto/googleapis/longrunning"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/metadata"
 )
 
 // CallOptions contains the retry settings for each method of Client.
@@ -81,7 +82,7 @@
 	CallOptions *CallOptions
 
 	// The metadata to be sent with each request.
-	xGoogHeader []string
+	Metadata metadata.MD
 }
 
 // NewClient creates a new video intelligence service client.
@@ -130,7 +131,7 @@
 func (c *Client) setGoogleClientInfo(keyval ...string) {
 	kv := append([]string{"gl-go", version.Go()}, keyval...)
 	kv = append(kv, "gapic", version.Repo, "gax", gax.Version, "grpc", grpc.Version)
-	c.xGoogHeader = []string{gax.XGoogHeader(kv...)}
+	c.Metadata = metadata.Pairs("x-goog-api-client", gax.XGoogHeader(kv...))
 }
 
 // AnnotateVideo performs asynchronous video annotation. Progress and results can be
@@ -138,7 +139,7 @@
 // Operation.metadata contains AnnotateVideoProgress (progress).
 // Operation.response contains AnnotateVideoResponse (results).
 func (c *Client) AnnotateVideo(ctx context.Context, req *videointelligencepb.AnnotateVideoRequest, opts ...gax.CallOption) (*AnnotateVideoOperation, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.AnnotateVideo[0:len(c.CallOptions.AnnotateVideo):len(c.CallOptions.AnnotateVideo)], opts...)
 	var resp *longrunningpb.Operation
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
diff --git a/videointelligence/apiv1beta2/doc.go b/videointelligence/apiv1beta2/doc.go
index b214286..8d97aa2 100644
--- a/videointelligence/apiv1beta2/doc.go
+++ b/videointelligence/apiv1beta2/doc.go
@@ -14,9 +14,11 @@
 
 // AUTO-GENERATED CODE. DO NOT EDIT.
 
-// Package videointelligence is an experimental, auto-generated package for the
+// Package videointelligence is an auto-generated package for the
 // Google Cloud Video Intelligence API.
 //
+//   NOTE: This package is in alpha. It is not stable, and is likely to be subject to changes.
+//
 // Google Cloud Video Intelligence API.
 package videointelligence // import "cloud.google.com/go/videointelligence/apiv1beta2"
 
@@ -25,11 +27,15 @@
 	"google.golang.org/grpc/metadata"
 )
 
-func insertXGoog(ctx context.Context, val []string) context.Context {
-	md, _ := metadata.FromOutgoingContext(ctx)
-	md = md.Copy()
-	md["x-goog-api-client"] = val
-	return metadata.NewOutgoingContext(ctx, md)
+func insertMetadata(ctx context.Context, mds ...metadata.MD) context.Context {
+	out, _ := metadata.FromOutgoingContext(ctx)
+	out = out.Copy()
+	for _, md := range mds {
+		for k, v := range md {
+			out[k] = append(out[k], v...)
+		}
+	}
+	return metadata.NewOutgoingContext(ctx, out)
 }
 
 // DefaultAuthScopes reports the default set of authentication scopes to use with this package.
diff --git a/videointelligence/apiv1beta2/mock_test.go b/videointelligence/apiv1beta2/mock_test.go
index fa6e84c..ddc98fb 100644
--- a/videointelligence/apiv1beta2/mock_test.go
+++ b/videointelligence/apiv1beta2/mock_test.go
@@ -118,12 +118,7 @@
 		Result: &longrunningpb.Operation_Response{Response: any},
 	})
 
-	var inputUri string = "inputUri1707300727"
-	var features []videointelligencepb.Feature = nil
-	var request = &videointelligencepb.AnnotateVideoRequest{
-		InputUri: inputUri,
-		Features: features,
-	}
+	var request *videointelligencepb.AnnotateVideoRequest = &videointelligencepb.AnnotateVideoRequest{}
 
 	c, err := NewClient(context.Background(), clientOpt)
 	if err != nil {
@@ -163,12 +158,7 @@
 		},
 	})
 
-	var inputUri string = "inputUri1707300727"
-	var features []videointelligencepb.Feature = nil
-	var request = &videointelligencepb.AnnotateVideoRequest{
-		InputUri: inputUri,
-		Features: features,
-	}
+	var request *videointelligencepb.AnnotateVideoRequest = &videointelligencepb.AnnotateVideoRequest{}
 
 	c, err := NewClient(context.Background(), clientOpt)
 	if err != nil {
diff --git a/videointelligence/apiv1beta2/video_intelligence_client.go b/videointelligence/apiv1beta2/video_intelligence_client.go
index 4dd4fef..936c093 100644
--- a/videointelligence/apiv1beta2/video_intelligence_client.go
+++ b/videointelligence/apiv1beta2/video_intelligence_client.go
@@ -30,6 +30,7 @@
 	longrunningpb "google.golang.org/genproto/googleapis/longrunning"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/metadata"
 )
 
 // CallOptions contains the retry settings for each method of Client.
@@ -81,7 +82,7 @@
 	CallOptions *CallOptions
 
 	// The metadata to be sent with each request.
-	xGoogHeader []string
+	Metadata metadata.MD
 }
 
 // NewClient creates a new video intelligence service client.
@@ -130,7 +131,7 @@
 func (c *Client) setGoogleClientInfo(keyval ...string) {
 	kv := append([]string{"gl-go", version.Go()}, keyval...)
 	kv = append(kv, "gapic", version.Repo, "gax", gax.Version, "grpc", grpc.Version)
-	c.xGoogHeader = []string{gax.XGoogHeader(kv...)}
+	c.Metadata = metadata.Pairs("x-goog-api-client", gax.XGoogHeader(kv...))
 }
 
 // AnnotateVideo performs asynchronous video annotation. Progress and results can be
@@ -138,7 +139,7 @@
 // Operation.metadata contains AnnotateVideoProgress (progress).
 // Operation.response contains AnnotateVideoResponse (results).
 func (c *Client) AnnotateVideo(ctx context.Context, req *videointelligencepb.AnnotateVideoRequest, opts ...gax.CallOption) (*AnnotateVideoOperation, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.AnnotateVideo[0:len(c.CallOptions.AnnotateVideo):len(c.CallOptions.AnnotateVideo)], opts...)
 	var resp *longrunningpb.Operation
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
diff --git a/vision/apiv1/doc.go b/vision/apiv1/doc.go
index ba3c99f..c852e15 100644
--- a/vision/apiv1/doc.go
+++ b/vision/apiv1/doc.go
@@ -16,6 +16,7 @@
 
 // Package vision is an auto-generated package for the
 // Google Cloud Vision API.
+
 //
 // Integrates Google Vision features, including image labeling, face, logo,
 // and landmark detection, optical character recognition (OCR), and detection
@@ -27,11 +28,15 @@
 	"google.golang.org/grpc/metadata"
 )
 
-func insertXGoog(ctx context.Context, val []string) context.Context {
-	md, _ := metadata.FromOutgoingContext(ctx)
-	md = md.Copy()
-	md["x-goog-api-client"] = val
-	return metadata.NewOutgoingContext(ctx, md)
+func insertMetadata(ctx context.Context, mds ...metadata.MD) context.Context {
+	out, _ := metadata.FromOutgoingContext(ctx)
+	out = out.Copy()
+	for _, md := range mds {
+		for k, v := range md {
+			out[k] = append(out[k], v...)
+		}
+	}
+	return metadata.NewOutgoingContext(ctx, out)
 }
 
 // DefaultAuthScopes reports the default set of authentication scopes to use with this package.
diff --git a/vision/apiv1/image_annotator_client.go b/vision/apiv1/image_annotator_client.go
index a7aebd5..5f430fc 100644
--- a/vision/apiv1/image_annotator_client.go
+++ b/vision/apiv1/image_annotator_client.go
@@ -27,6 +27,7 @@
 	visionpb "google.golang.org/genproto/googleapis/cloud/vision/v1"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/metadata"
 )
 
 // ImageAnnotatorCallOptions contains the retry settings for each method of ImageAnnotatorClient.
@@ -73,7 +74,7 @@
 	CallOptions *ImageAnnotatorCallOptions
 
 	// The metadata to be sent with each request.
-	xGoogHeader []string
+	Metadata metadata.MD
 }
 
 // NewImageAnnotatorClient creates a new image annotator client.
@@ -113,12 +114,12 @@
 func (c *ImageAnnotatorClient) setGoogleClientInfo(keyval ...string) {
 	kv := append([]string{"gl-go", version.Go()}, keyval...)
 	kv = append(kv, "gapic", version.Repo, "gax", gax.Version, "grpc", grpc.Version)
-	c.xGoogHeader = []string{gax.XGoogHeader(kv...)}
+	c.Metadata = metadata.Pairs("x-goog-api-client", gax.XGoogHeader(kv...))
 }
 
 // BatchAnnotateImages run image detection and annotation for a batch of images.
 func (c *ImageAnnotatorClient) BatchAnnotateImages(ctx context.Context, req *visionpb.BatchAnnotateImagesRequest, opts ...gax.CallOption) (*visionpb.BatchAnnotateImagesResponse, error) {
-	ctx = insertXGoog(ctx, c.xGoogHeader)
+	ctx = insertMetadata(ctx, c.Metadata)
 	opts = append(c.CallOptions.BatchAnnotateImages[0:len(c.CallOptions.BatchAnnotateImages):len(c.CallOptions.BatchAnnotateImages)], opts...)
 	var resp *visionpb.BatchAnnotateImagesResponse
 	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {