feat(documentai): start generating apiv1beta3 (#3595)

diff --git a/documentai/apiv1beta3/doc.go b/documentai/apiv1beta3/doc.go
new file mode 100644
index 0000000..9f02ae5
--- /dev/null
+++ b/documentai/apiv1beta3/doc.go
@@ -0,0 +1,118 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Code generated by protoc-gen-go_gapic. DO NOT EDIT.
+
+// Package documentai is an auto-generated package for the
+// Cloud Document AI API.
+//
+// Service to parse structured information from unstructured or
+// semi-structured documents using state-of-the-art Google AI such as natural
+// language, computer vision, translation, and AutoML.
+//
+// Use of Context
+//
+// The ctx passed to NewClient is used for authentication requests and
+// for creating the underlying connection, but is not used for subsequent calls.
+// Individual methods on the client use the ctx given to them.
+//
+// To close the open connection, use the Close() method.
+//
+// For information about setting deadlines, reusing contexts, and more
+// please visit pkg.go.dev/cloud.google.com/go.
+package documentai // import "cloud.google.com/go/documentai/apiv1beta3"
+
+import (
+	"context"
+	"os"
+	"runtime"
+	"strconv"
+	"strings"
+	"unicode"
+
+	"google.golang.org/api/option"
+	"google.golang.org/grpc/metadata"
+)
+
+// For more information on implementing a client constructor hook, see
+// https://github.com/googleapis/google-cloud-go/wiki/Customizing-constructors.
+type clientHookParams struct{}
+type clientHook func(context.Context, clientHookParams) ([]option.ClientOption, error)
+
+const versionClient = "20210121"
+
+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)
+}
+
+func checkDisableDeadlines() (bool, error) {
+	raw, ok := os.LookupEnv("GOOGLE_API_GO_EXPERIMENTAL_DISABLE_DEFAULT_DEADLINE")
+	if !ok {
+		return false, nil
+	}
+
+	b, err := strconv.ParseBool(raw)
+	return b, err
+}
+
+// DefaultAuthScopes reports the default set of authentication scopes to use with this package.
+func DefaultAuthScopes() []string {
+	return []string{
+		"https://www.googleapis.com/auth/cloud-platform",
+	}
+}
+
+// versionGo returns the Go runtime version. The returned string
+// has no whitespace, suitable for reporting in header.
+func versionGo() string {
+	const develPrefix = "devel +"
+
+	s := runtime.Version()
+	if strings.HasPrefix(s, develPrefix) {
+		s = s[len(develPrefix):]
+		if p := strings.IndexFunc(s, unicode.IsSpace); p >= 0 {
+			s = s[:p]
+		}
+		return s
+	}
+
+	notSemverRune := func(r rune) bool {
+		return !strings.ContainsRune("0123456789.", r)
+	}
+
+	if strings.HasPrefix(s, "go1") {
+		s = s[2:]
+		var prerelease string
+		if p := strings.IndexFunc(s, notSemverRune); p >= 0 {
+			s, prerelease = s[:p], s[p:]
+		}
+		if strings.HasSuffix(s, ".") {
+			s += "0"
+		} else if strings.Count(s, ".") < 2 {
+			s += ".0"
+		}
+		if prerelease != "" {
+			s += "-" + prerelease
+		}
+		return s
+	}
+	return "UNKNOWN"
+}
diff --git a/documentai/apiv1beta3/document_processor_client.go b/documentai/apiv1beta3/document_processor_client.go
new file mode 100644
index 0000000..5ccaa0c
--- /dev/null
+++ b/documentai/apiv1beta3/document_processor_client.go
@@ -0,0 +1,404 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Code generated by protoc-gen-go_gapic. DO NOT EDIT.
+
+package documentai
+
+import (
+	"context"
+	"fmt"
+	"math"
+	"net/url"
+	"time"
+
+	"cloud.google.com/go/longrunning"
+	lroauto "cloud.google.com/go/longrunning/autogen"
+	gax "github.com/googleapis/gax-go/v2"
+	"google.golang.org/api/option"
+	"google.golang.org/api/option/internaloption"
+	gtransport "google.golang.org/api/transport/grpc"
+	documentaipb "google.golang.org/genproto/googleapis/cloud/documentai/v1beta3"
+	longrunningpb "google.golang.org/genproto/googleapis/longrunning"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/metadata"
+)
+
+var newDocumentProcessorClientHook clientHook
+
+// DocumentProcessorCallOptions contains the retry settings for each method of DocumentProcessorClient.
+type DocumentProcessorCallOptions struct {
+	ProcessDocument       []gax.CallOption
+	BatchProcessDocuments []gax.CallOption
+	ReviewDocument        []gax.CallOption
+}
+
+func defaultDocumentProcessorClientOptions() []option.ClientOption {
+	return []option.ClientOption{
+		internaloption.WithDefaultEndpoint("us-documentai.googleapis.com:443"),
+		internaloption.WithDefaultMTLSEndpoint("us-documentai.mtls.googleapis.com:443"),
+		internaloption.WithDefaultAudience("https://us-documentai.googleapis.com/"),
+		internaloption.WithDefaultScopes(DefaultAuthScopes()...),
+		option.WithGRPCDialOption(grpc.WithDisableServiceConfig()),
+		option.WithGRPCDialOption(grpc.WithDefaultCallOptions(
+			grpc.MaxCallRecvMsgSize(math.MaxInt32))),
+	}
+}
+
+func defaultDocumentProcessorCallOptions() *DocumentProcessorCallOptions {
+	return &DocumentProcessorCallOptions{
+		ProcessDocument: []gax.CallOption{
+			gax.WithRetry(func() gax.Retryer {
+				return gax.OnCodes([]codes.Code{
+					codes.DeadlineExceeded,
+					codes.Unavailable,
+				}, gax.Backoff{
+					Initial:    100 * time.Millisecond,
+					Max:        60000 * time.Millisecond,
+					Multiplier: 1.30,
+				})
+			}),
+		},
+		BatchProcessDocuments: []gax.CallOption{
+			gax.WithRetry(func() gax.Retryer {
+				return gax.OnCodes([]codes.Code{
+					codes.DeadlineExceeded,
+					codes.Unavailable,
+				}, gax.Backoff{
+					Initial:    100 * time.Millisecond,
+					Max:        60000 * time.Millisecond,
+					Multiplier: 1.30,
+				})
+			}),
+		},
+		ReviewDocument: []gax.CallOption{
+			gax.WithRetry(func() gax.Retryer {
+				return gax.OnCodes([]codes.Code{
+					codes.DeadlineExceeded,
+					codes.Unavailable,
+				}, gax.Backoff{
+					Initial:    100 * time.Millisecond,
+					Max:        60000 * time.Millisecond,
+					Multiplier: 1.30,
+				})
+			}),
+		},
+	}
+}
+
+// DocumentProcessorClient is a client for interacting with Cloud Document AI API.
+//
+// Methods, except Close, may be called concurrently. However, fields must not be modified concurrently with method calls.
+type DocumentProcessorClient struct {
+	// Connection pool of gRPC connections to the service.
+	connPool gtransport.ConnPool
+
+	// flag to opt out of default deadlines via GOOGLE_API_GO_EXPERIMENTAL_DISABLE_DEFAULT_DEADLINE
+	disableDeadlines bool
+
+	// The gRPC API client.
+	documentProcessorClient documentaipb.DocumentProcessorServiceClient
+
+	// LROClient is used internally to handle longrunning operations.
+	// It is exposed so that its CallOptions can be modified if required.
+	// Users should not Close this client.
+	LROClient *lroauto.OperationsClient
+
+	// The call options for this service.
+	CallOptions *DocumentProcessorCallOptions
+
+	// The x-goog-* metadata to be sent with each request.
+	xGoogMetadata metadata.MD
+}
+
+// NewDocumentProcessorClient creates a new document processor service client.
+//
+// Service to call Cloud DocumentAI to process documents according to the
+// processor’s definition. Processors are built using state-of-the-art Google
+// AI such as natural language, computer vision, and translation to extract
+// structured information from unstructured or semi-structured documents.
+func NewDocumentProcessorClient(ctx context.Context, opts ...option.ClientOption) (*DocumentProcessorClient, error) {
+	clientOpts := defaultDocumentProcessorClientOptions()
+
+	if newDocumentProcessorClientHook != nil {
+		hookOpts, err := newDocumentProcessorClientHook(ctx, clientHookParams{})
+		if err != nil {
+			return nil, err
+		}
+		clientOpts = append(clientOpts, hookOpts...)
+	}
+
+	disableDeadlines, err := checkDisableDeadlines()
+	if err != nil {
+		return nil, err
+	}
+
+	connPool, err := gtransport.DialPool(ctx, append(clientOpts, opts...)...)
+	if err != nil {
+		return nil, err
+	}
+	c := &DocumentProcessorClient{
+		connPool:         connPool,
+		disableDeadlines: disableDeadlines,
+		CallOptions:      defaultDocumentProcessorCallOptions(),
+
+		documentProcessorClient: documentaipb.NewDocumentProcessorServiceClient(connPool),
+	}
+	c.setGoogleClientInfo()
+
+	c.LROClient, err = lroauto.NewOperationsClient(ctx, gtransport.WithConnPool(connPool))
+	if err != nil {
+		// This error "should not happen", since we are just reusing old connection pool
+		// and never actually need to dial.
+		// If this does happen, we could leak connp. However, we cannot close conn:
+		// If the user invoked the constructor with option.WithGRPCConn,
+		// we would close a connection that's still in use.
+		// TODO: investigate error conditions.
+		return nil, err
+	}
+	return c, nil
+}
+
+// Connection returns a connection to the API service.
+//
+// Deprecated.
+func (c *DocumentProcessorClient) Connection() *grpc.ClientConn {
+	return c.connPool.Conn()
+}
+
+// Close closes the connection to the API service. The user should invoke this when
+// the client is no longer required.
+func (c *DocumentProcessorClient) Close() error {
+	return c.connPool.Close()
+}
+
+// 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 *DocumentProcessorClient) setGoogleClientInfo(keyval ...string) {
+	kv := append([]string{"gl-go", versionGo()}, keyval...)
+	kv = append(kv, "gapic", versionClient, "gax", gax.Version, "grpc", grpc.Version)
+	c.xGoogMetadata = metadata.Pairs("x-goog-api-client", gax.XGoogHeader(kv...))
+}
+
+// ProcessDocument processes a single document.
+func (c *DocumentProcessorClient) ProcessDocument(ctx context.Context, req *documentaipb.ProcessRequest, opts ...gax.CallOption) (*documentaipb.ProcessResponse, error) {
+	if _, ok := ctx.Deadline(); !ok && !c.disableDeadlines {
+		cctx, cancel := context.WithTimeout(ctx, 120000*time.Millisecond)
+		defer cancel()
+		ctx = cctx
+	}
+	md := metadata.Pairs("x-goog-request-params", fmt.Sprintf("%s=%v", "name", url.QueryEscape(req.GetName())))
+	ctx = insertMetadata(ctx, c.xGoogMetadata, md)
+	opts = append(c.CallOptions.ProcessDocument[0:len(c.CallOptions.ProcessDocument):len(c.CallOptions.ProcessDocument)], opts...)
+	var resp *documentaipb.ProcessResponse
+	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
+		var err error
+		resp, err = c.documentProcessorClient.ProcessDocument(ctx, req, settings.GRPC...)
+		return err
+	}, opts...)
+	if err != nil {
+		return nil, err
+	}
+	return resp, nil
+}
+
+// BatchProcessDocuments lRO endpoint to batch process many documents. The output is written
+// to Cloud Storage as JSON in the [Document] format.
+func (c *DocumentProcessorClient) BatchProcessDocuments(ctx context.Context, req *documentaipb.BatchProcessRequest, opts ...gax.CallOption) (*BatchProcessDocumentsOperation, error) {
+	if _, ok := ctx.Deadline(); !ok && !c.disableDeadlines {
+		cctx, cancel := context.WithTimeout(ctx, 120000*time.Millisecond)
+		defer cancel()
+		ctx = cctx
+	}
+	md := metadata.Pairs("x-goog-request-params", fmt.Sprintf("%s=%v", "name", url.QueryEscape(req.GetName())))
+	ctx = insertMetadata(ctx, c.xGoogMetadata, md)
+	opts = append(c.CallOptions.BatchProcessDocuments[0:len(c.CallOptions.BatchProcessDocuments):len(c.CallOptions.BatchProcessDocuments)], opts...)
+	var resp *longrunningpb.Operation
+	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
+		var err error
+		resp, err = c.documentProcessorClient.BatchProcessDocuments(ctx, req, settings.GRPC...)
+		return err
+	}, opts...)
+	if err != nil {
+		return nil, err
+	}
+	return &BatchProcessDocumentsOperation{
+		lro: longrunning.InternalNewOperation(c.LROClient, resp),
+	}, nil
+}
+
+// ReviewDocument send a document for Human Review. The input document should be processed by
+// the specified processor.
+func (c *DocumentProcessorClient) ReviewDocument(ctx context.Context, req *documentaipb.ReviewDocumentRequest, opts ...gax.CallOption) (*ReviewDocumentOperation, error) {
+	if _, ok := ctx.Deadline(); !ok && !c.disableDeadlines {
+		cctx, cancel := context.WithTimeout(ctx, 120000*time.Millisecond)
+		defer cancel()
+		ctx = cctx
+	}
+	md := metadata.Pairs("x-goog-request-params", fmt.Sprintf("%s=%v", "human_review_config", url.QueryEscape(req.GetHumanReviewConfig())))
+	ctx = insertMetadata(ctx, c.xGoogMetadata, md)
+	opts = append(c.CallOptions.ReviewDocument[0:len(c.CallOptions.ReviewDocument):len(c.CallOptions.ReviewDocument)], opts...)
+	var resp *longrunningpb.Operation
+	err := gax.Invoke(ctx, func(ctx context.Context, settings gax.CallSettings) error {
+		var err error
+		resp, err = c.documentProcessorClient.ReviewDocument(ctx, req, settings.GRPC...)
+		return err
+	}, opts...)
+	if err != nil {
+		return nil, err
+	}
+	return &ReviewDocumentOperation{
+		lro: longrunning.InternalNewOperation(c.LROClient, resp),
+	}, nil
+}
+
+// BatchProcessDocumentsOperation manages a long-running operation from BatchProcessDocuments.
+type BatchProcessDocumentsOperation struct {
+	lro *longrunning.Operation
+}
+
+// BatchProcessDocumentsOperation returns a new BatchProcessDocumentsOperation from a given name.
+// The name must be that of a previously created BatchProcessDocumentsOperation, possibly from a different process.
+func (c *DocumentProcessorClient) BatchProcessDocumentsOperation(name string) *BatchProcessDocumentsOperation {
+	return &BatchProcessDocumentsOperation{
+		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 *BatchProcessDocumentsOperation) Wait(ctx context.Context, opts ...gax.CallOption) (*documentaipb.BatchProcessResponse, error) {
+	var resp documentaipb.BatchProcessResponse
+	if err := op.lro.WaitWithInterval(ctx, &resp, time.Minute, 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 *BatchProcessDocumentsOperation) Poll(ctx context.Context, opts ...gax.CallOption) (*documentaipb.BatchProcessResponse, error) {
+	var resp documentaipb.BatchProcessResponse
+	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 *BatchProcessDocumentsOperation) Metadata() (*documentaipb.BatchProcessMetadata, error) {
+	var meta documentaipb.BatchProcessMetadata
+	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 *BatchProcessDocumentsOperation) 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 *BatchProcessDocumentsOperation) Name() string {
+	return op.lro.Name()
+}
+
+// ReviewDocumentOperation manages a long-running operation from ReviewDocument.
+type ReviewDocumentOperation struct {
+	lro *longrunning.Operation
+}
+
+// ReviewDocumentOperation returns a new ReviewDocumentOperation from a given name.
+// The name must be that of a previously created ReviewDocumentOperation, possibly from a different process.
+func (c *DocumentProcessorClient) ReviewDocumentOperation(name string) *ReviewDocumentOperation {
+	return &ReviewDocumentOperation{
+		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 *ReviewDocumentOperation) Wait(ctx context.Context, opts ...gax.CallOption) (*documentaipb.ReviewDocumentResponse, error) {
+	var resp documentaipb.ReviewDocumentResponse
+	if err := op.lro.WaitWithInterval(ctx, &resp, time.Minute, 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 *ReviewDocumentOperation) Poll(ctx context.Context, opts ...gax.CallOption) (*documentaipb.ReviewDocumentResponse, error) {
+	var resp documentaipb.ReviewDocumentResponse
+	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 *ReviewDocumentOperation) Metadata() (*documentaipb.ReviewDocumentOperationMetadata, error) {
+	var meta documentaipb.ReviewDocumentOperationMetadata
+	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 *ReviewDocumentOperation) 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 *ReviewDocumentOperation) Name() string {
+	return op.lro.Name()
+}
diff --git a/documentai/apiv1beta3/document_processor_client_example_test.go b/documentai/apiv1beta3/document_processor_client_example_test.go
new file mode 100644
index 0000000..ccddcfc
--- /dev/null
+++ b/documentai/apiv1beta3/document_processor_client_example_test.go
@@ -0,0 +1,104 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Code generated by protoc-gen-go_gapic. DO NOT EDIT.
+
+package documentai_test
+
+import (
+	"context"
+
+	documentai "cloud.google.com/go/documentai/apiv1beta3"
+	documentaipb "google.golang.org/genproto/googleapis/cloud/documentai/v1beta3"
+)
+
+func ExampleNewDocumentProcessorClient() {
+	ctx := context.Background()
+	c, err := documentai.NewDocumentProcessorClient(ctx)
+	if err != nil {
+		// TODO: Handle error.
+	}
+	// TODO: Use client.
+	_ = c
+}
+
+func ExampleDocumentProcessorClient_ProcessDocument() {
+	// import documentaipb "google.golang.org/genproto/googleapis/cloud/documentai/v1beta3"
+
+	ctx := context.Background()
+	c, err := documentai.NewDocumentProcessorClient(ctx)
+	if err != nil {
+		// TODO: Handle error.
+	}
+
+	req := &documentaipb.ProcessRequest{
+		// TODO: Fill request struct fields.
+	}
+	resp, err := c.ProcessDocument(ctx, req)
+	if err != nil {
+		// TODO: Handle error.
+	}
+	// TODO: Use resp.
+	_ = resp
+}
+
+func ExampleDocumentProcessorClient_BatchProcessDocuments() {
+	// import documentaipb "google.golang.org/genproto/googleapis/cloud/documentai/v1beta3"
+
+	ctx := context.Background()
+	c, err := documentai.NewDocumentProcessorClient(ctx)
+	if err != nil {
+		// TODO: Handle error.
+	}
+
+	req := &documentaipb.BatchProcessRequest{
+		// TODO: Fill request struct fields.
+	}
+	op, err := c.BatchProcessDocuments(ctx, req)
+	if err != nil {
+		// TODO: Handle error.
+	}
+
+	resp, err := op.Wait(ctx)
+	if err != nil {
+		// TODO: Handle error.
+	}
+	// TODO: Use resp.
+	_ = resp
+}
+
+func ExampleDocumentProcessorClient_ReviewDocument() {
+	// import documentaipb "google.golang.org/genproto/googleapis/cloud/documentai/v1beta3"
+
+	ctx := context.Background()
+	c, err := documentai.NewDocumentProcessorClient(ctx)
+	if err != nil {
+		// TODO: Handle error.
+	}
+
+	req := &documentaipb.ReviewDocumentRequest{
+		// TODO: Fill request struct fields.
+	}
+	op, err := c.ReviewDocument(ctx, req)
+	if err != nil {
+		// TODO: Handle error.
+	}
+
+	resp, err := op.Wait(ctx)
+	if err != nil {
+		// TODO: Handle error.
+	}
+	// TODO: Use resp.
+	_ = resp
+}
diff --git a/internal/.repo-metadata-full.json b/internal/.repo-metadata-full.json
index 63a88bc..c77336e 100644
--- a/internal/.repo-metadata-full.json
+++ b/internal/.repo-metadata-full.json
@@ -367,6 +367,14 @@
     "docs_url": "https://pkg.go.dev/cloud.google.com/go/dlp/apiv2",
     "release_level": "ga"
   },
+  "cloud.google.com/go/documentai/apiv1beta3": {
+    "distribution_name": "cloud.google.com/go/documentai/apiv1beta3",
+    "description": "Cloud Document AI API",
+    "language": "Go",
+    "client_library_type": "generated",
+    "docs_url": "https://pkg.go.dev/cloud.google.com/go/documentai/apiv1beta3",
+    "release_level": "beta"
+  },
   "cloud.google.com/go/errorreporting": {
     "distribution_name": "cloud.google.com/go/errorreporting",
     "description": "Cloud Error Reporting API",
diff --git a/internal/gapicgen/generator/config.go b/internal/gapicgen/generator/config.go
index ed13604..c606aed 100644
--- a/internal/gapicgen/generator/config.go
+++ b/internal/gapicgen/generator/config.go
@@ -941,6 +941,14 @@
 		releaseLevel:          "alpha",
 	},
 	{
+		inputDirectoryPath:    "google/cloud/documentai/v1beta3",
+		pkg:                   "documentai",
+		importPath:            "cloud.google.com/go/documentai/apiv1beta3",
+		gRPCServiceConfigPath: "google/cloud/documentai/v1beta3/documentai_v1beta3_grpc_service_config.json",
+		apiServiceConfigPath:  "google/cloud/documentai/v1beta3/documentai_v1beta3.yaml",
+		releaseLevel:          "beta",
+	},
+	{
 		inputDirectoryPath:    "google/api/servicemanagement/v1",
 		pkg:                   "servicemanagement",
 		importPath:            "cloud.google.com/go/servicemanagement/apiv1",