all: autogenerated update (2019-08-11)

Update:
- cloudtasks/v2beta2
diff --git a/cloudtasks/v2beta2/cloudtasks-api.json b/cloudtasks/v2beta2/cloudtasks-api.json
index 1930fce..6a914ff 100644
--- a/cloudtasks/v2beta2/cloudtasks-api.json
+++ b/cloudtasks/v2beta2/cloudtasks-api.json
@@ -786,7 +786,7 @@
       }
     }
   },
-  "revision": "20190618",
+  "revision": "20190531",
   "rootUrl": "https://cloudtasks.googleapis.com/",
   "schemas": {
     "AcknowledgeTaskRequest": {
@@ -1025,7 +1025,7 @@
           "type": "string"
         },
         "leaseDuration": {
-          "description": "Required.\n\nThe duration of the lease.\n\nEach task returned in the response will\nhave its schedule_time set to the current\ntime plus the `lease_duration`. The task is leased until its\nschedule_time; thus, the task will not be\nreturned to another LeaseTasks call\nbefore its schedule_time.\n\n\nAfter the worker has successfully finished the work associated\nwith the task, the worker must call via\nAcknowledgeTask before the\nschedule_time. Otherwise the task will be\nreturned to a later LeaseTasks call so\nthat another worker can retry it.\n\nThe maximum lease duration is 1 week.\n`lease_duration` will be truncated to the nearest second.",
+          "description": "\nAfter the worker has successfully finished the work associated\nwith the task, the worker must call via\nAcknowledgeTask before the\nschedule_time. Otherwise the task will be\nreturned to a later LeaseTasks call so\nthat another worker can retry it.\n\nThe maximum lease duration is 1 week.\n`lease_duration` will be truncated to the nearest second.",
           "format": "google-duration",
           "type": "string"
         },
diff --git a/cloudtasks/v2beta2/cloudtasks-gen.go b/cloudtasks/v2beta2/cloudtasks-gen.go
index 2ca9194..48c29eb 100644
--- a/cloudtasks/v2beta2/cloudtasks-gen.go
+++ b/cloudtasks/v2beta2/cloudtasks-gen.go
@@ -1088,19 +1088,7 @@
 	// tag will be displayed as empty in Cloud Tasks.
 	Filter string `json:"filter,omitempty"`
 
-	// LeaseDuration: Required.
-	//
-	// The duration of the lease.
-	//
-	// Each task returned in the response will
-	// have its schedule_time set to the current
-	// time plus the `lease_duration`. The task is leased until
-	// its
-	// schedule_time; thus, the task will not be
-	// returned to another LeaseTasks call
-	// before its schedule_time.
-	//
-	//
+	// LeaseDuration:
 	// After the worker has successfully finished the work associated
 	// with the task, the worker must call via
 	// AcknowledgeTask before the