diff --git a/google/cloud/clouddms_v1/services/data_migration_service/async_client.py b/google/cloud/clouddms_v1/services/data_migration_service/async_client.py
index 73e3ca5..726cc38 100644
--- a/google/cloud/clouddms_v1/services/data_migration_service/async_client.py
+++ b/google/cloud/clouddms_v1/services/data_migration_service/async_client.py
@@ -19,13 +19,15 @@
 from typing import Dict, Sequence, Tuple, Type, Union
 import pkg_resources
 
-import google.api_core.client_options as ClientOptions  # type: ignore
+from google.api_core.client_options import ClientOptions  # type: ignore
 from google.api_core import exceptions as core_exceptions  # type: ignore
 from google.api_core import gapic_v1  # type: ignore
 from google.api_core import retry as retries  # type: ignore
 from google.auth import credentials as ga_credentials  # type: ignore
 from google.oauth2 import service_account  # type: ignore
 
+OptionalRetry = Union[retries.Retry, object]
+
 from google.api_core import operation  # type: ignore
 from google.api_core import operation_async  # type: ignore
 from google.cloud.clouddms_v1.services.data_migration_service import pagers
@@ -180,17 +182,17 @@ def __init__(
 
     async def list_migration_jobs(
         self,
-        request: clouddms.ListMigrationJobsRequest = None,
+        request: Union[clouddms.ListMigrationJobsRequest, dict] = None,
         *,
         parent: str = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> pagers.ListMigrationJobsAsyncPager:
         r"""Lists migration jobs in a given project and location.
 
         Args:
-            request (:class:`google.cloud.clouddms_v1.types.ListMigrationJobsRequest`):
+            request (Union[google.cloud.clouddms_v1.types.ListMigrationJobsRequest, dict]):
                 The request object. Retrieve a list of all migration
                 jobs in a given project and location.
             parent (:class:`str`):
@@ -260,17 +262,17 @@ async def list_migration_jobs(
 
     async def get_migration_job(
         self,
-        request: clouddms.GetMigrationJobRequest = None,
+        request: Union[clouddms.GetMigrationJobRequest, dict] = None,
         *,
         name: str = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> clouddms_resources.MigrationJob:
         r"""Gets details of a single migration job.
 
         Args:
-            request (:class:`google.cloud.clouddms_v1.types.GetMigrationJobRequest`):
+            request (Union[google.cloud.clouddms_v1.types.GetMigrationJobRequest, dict]):
                 The request object. Request message for
                 'GetMigrationJob' request.
             name (:class:`str`):
@@ -331,12 +333,12 @@ async def get_migration_job(
 
     async def create_migration_job(
         self,
-        request: clouddms.CreateMigrationJobRequest = None,
+        request: Union[clouddms.CreateMigrationJobRequest, dict] = None,
         *,
         parent: str = None,
         migration_job: clouddms_resources.MigrationJob = None,
         migration_job_id: str = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> operation_async.AsyncOperation:
@@ -344,7 +346,7 @@ async def create_migration_job(
         location.
 
         Args:
-            request (:class:`google.cloud.clouddms_v1.types.CreateMigrationJobRequest`):
+            request (Union[google.cloud.clouddms_v1.types.CreateMigrationJobRequest, dict]):
                 The request object. Request message to create a new
                 Database Migration Service migration job in the
                 specified project and region.
@@ -437,18 +439,18 @@ async def create_migration_job(
 
     async def update_migration_job(
         self,
-        request: clouddms.UpdateMigrationJobRequest = None,
+        request: Union[clouddms.UpdateMigrationJobRequest, dict] = None,
         *,
         migration_job: clouddms_resources.MigrationJob = None,
         update_mask: field_mask_pb2.FieldMask = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> operation_async.AsyncOperation:
         r"""Updates the parameters of a single migration job.
 
         Args:
-            request (:class:`google.cloud.clouddms_v1.types.UpdateMigrationJobRequest`):
+            request (Union[google.cloud.clouddms_v1.types.UpdateMigrationJobRequest, dict]):
                 The request object. Request message for
                 'UpdateMigrationJob' request.
             migration_job (:class:`google.cloud.clouddms_v1.types.MigrationJob`):
@@ -534,17 +536,17 @@ async def update_migration_job(
 
     async def delete_migration_job(
         self,
-        request: clouddms.DeleteMigrationJobRequest = None,
+        request: Union[clouddms.DeleteMigrationJobRequest, dict] = None,
         *,
         name: str = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> operation_async.AsyncOperation:
         r"""Deletes a single migration job.
 
         Args:
-            request (:class:`google.cloud.clouddms_v1.types.DeleteMigrationJobRequest`):
+            request (Union[google.cloud.clouddms_v1.types.DeleteMigrationJobRequest, dict]):
                 The request object. Request message for
                 'DeleteMigrationJob' request.
             name (:class:`str`):
@@ -626,16 +628,16 @@ async def delete_migration_job(
 
     async def start_migration_job(
         self,
-        request: clouddms.StartMigrationJobRequest = None,
+        request: Union[clouddms.StartMigrationJobRequest, dict] = None,
         *,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> operation_async.AsyncOperation:
         r"""Start an already created migration job.
 
         Args:
-            request (:class:`google.cloud.clouddms_v1.types.StartMigrationJobRequest`):
+            request (Union[google.cloud.clouddms_v1.types.StartMigrationJobRequest, dict]):
                 The request object. Request message for
                 'StartMigrationJob' request.
             retry (google.api_core.retry.Retry): Designation of what errors, if any,
@@ -687,16 +689,16 @@ async def start_migration_job(
 
     async def stop_migration_job(
         self,
-        request: clouddms.StopMigrationJobRequest = None,
+        request: Union[clouddms.StopMigrationJobRequest, dict] = None,
         *,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> operation_async.AsyncOperation:
         r"""Stops a running migration job.
 
         Args:
-            request (:class:`google.cloud.clouddms_v1.types.StopMigrationJobRequest`):
+            request (Union[google.cloud.clouddms_v1.types.StopMigrationJobRequest, dict]):
                 The request object. Request message for
                 'StopMigrationJob' request.
             retry (google.api_core.retry.Retry): Designation of what errors, if any,
@@ -748,9 +750,9 @@ async def stop_migration_job(
 
     async def resume_migration_job(
         self,
-        request: clouddms.ResumeMigrationJobRequest = None,
+        request: Union[clouddms.ResumeMigrationJobRequest, dict] = None,
         *,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> operation_async.AsyncOperation:
@@ -758,7 +760,7 @@ async def resume_migration_job(
         is resumable (was stopped during CDC phase).
 
         Args:
-            request (:class:`google.cloud.clouddms_v1.types.ResumeMigrationJobRequest`):
+            request (Union[google.cloud.clouddms_v1.types.ResumeMigrationJobRequest, dict]):
                 The request object. Request message for
                 'ResumeMigrationJob' request.
             retry (google.api_core.retry.Retry): Designation of what errors, if any,
@@ -810,9 +812,9 @@ async def resume_migration_job(
 
     async def promote_migration_job(
         self,
-        request: clouddms.PromoteMigrationJobRequest = None,
+        request: Union[clouddms.PromoteMigrationJobRequest, dict] = None,
         *,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> operation_async.AsyncOperation:
@@ -821,7 +823,7 @@ async def promote_migration_job(
         standalone database.
 
         Args:
-            request (:class:`google.cloud.clouddms_v1.types.PromoteMigrationJobRequest`):
+            request (Union[google.cloud.clouddms_v1.types.PromoteMigrationJobRequest, dict]):
                 The request object. Request message for
                 'PromoteMigrationJob' request.
             retry (google.api_core.retry.Retry): Designation of what errors, if any,
@@ -873,9 +875,9 @@ async def promote_migration_job(
 
     async def verify_migration_job(
         self,
-        request: clouddms.VerifyMigrationJobRequest = None,
+        request: Union[clouddms.VerifyMigrationJobRequest, dict] = None,
         *,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> operation_async.AsyncOperation:
@@ -884,7 +886,7 @@ async def verify_migration_job(
         prerequisites are met.
 
         Args:
-            request (:class:`google.cloud.clouddms_v1.types.VerifyMigrationJobRequest`):
+            request (Union[google.cloud.clouddms_v1.types.VerifyMigrationJobRequest, dict]):
                 The request object. Request message for
                 'VerifyMigrationJob' request.
             retry (google.api_core.retry.Retry): Designation of what errors, if any,
@@ -936,9 +938,9 @@ async def verify_migration_job(
 
     async def restart_migration_job(
         self,
-        request: clouddms.RestartMigrationJobRequest = None,
+        request: Union[clouddms.RestartMigrationJobRequest, dict] = None,
         *,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> operation_async.AsyncOperation:
@@ -947,7 +949,7 @@ async def restart_migration_job(
         starting the migration process from scratch.
 
         Args:
-            request (:class:`google.cloud.clouddms_v1.types.RestartMigrationJobRequest`):
+            request (Union[google.cloud.clouddms_v1.types.RestartMigrationJobRequest, dict]):
                 The request object. Request message for
                 'RestartMigrationJob' request.
             retry (google.api_core.retry.Retry): Designation of what errors, if any,
@@ -999,9 +1001,9 @@ async def restart_migration_job(
 
     async def generate_ssh_script(
         self,
-        request: clouddms.GenerateSshScriptRequest = None,
+        request: Union[clouddms.GenerateSshScriptRequest, dict] = None,
         *,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> clouddms.SshScript:
@@ -1009,7 +1011,7 @@ async def generate_ssh_script(
         reverse SSH connectivity.
 
         Args:
-            request (:class:`google.cloud.clouddms_v1.types.GenerateSshScriptRequest`):
+            request (Union[google.cloud.clouddms_v1.types.GenerateSshScriptRequest, dict]):
                 The request object. Request message for
                 'GenerateSshScript' request.
             retry (google.api_core.retry.Retry): Designation of what errors, if any,
@@ -1051,10 +1053,10 @@ async def generate_ssh_script(
 
     async def list_connection_profiles(
         self,
-        request: clouddms.ListConnectionProfilesRequest = None,
+        request: Union[clouddms.ListConnectionProfilesRequest, dict] = None,
         *,
         parent: str = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> pagers.ListConnectionProfilesAsyncPager:
@@ -1062,7 +1064,7 @@ async def list_connection_profiles(
         project and location.
 
         Args:
-            request (:class:`google.cloud.clouddms_v1.types.ListConnectionProfilesRequest`):
+            request (Union[google.cloud.clouddms_v1.types.ListConnectionProfilesRequest, dict]):
                 The request object. Request message for
                 'ListConnectionProfiles' request.
             parent (:class:`str`):
@@ -1132,17 +1134,17 @@ async def list_connection_profiles(
 
     async def get_connection_profile(
         self,
-        request: clouddms.GetConnectionProfileRequest = None,
+        request: Union[clouddms.GetConnectionProfileRequest, dict] = None,
         *,
         name: str = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> clouddms_resources.ConnectionProfile:
         r"""Gets details of a single connection profile.
 
         Args:
-            request (:class:`google.cloud.clouddms_v1.types.GetConnectionProfileRequest`):
+            request (Union[google.cloud.clouddms_v1.types.GetConnectionProfileRequest, dict]):
                 The request object. Request message for
                 'GetConnectionProfile' request.
             name (:class:`str`):
@@ -1201,12 +1203,12 @@ async def get_connection_profile(
 
     async def create_connection_profile(
         self,
-        request: clouddms.CreateConnectionProfileRequest = None,
+        request: Union[clouddms.CreateConnectionProfileRequest, dict] = None,
         *,
         parent: str = None,
         connection_profile: clouddms_resources.ConnectionProfile = None,
         connection_profile_id: str = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> operation_async.AsyncOperation:
@@ -1214,7 +1216,7 @@ async def create_connection_profile(
         and location.
 
         Args:
-            request (:class:`google.cloud.clouddms_v1.types.CreateConnectionProfileRequest`):
+            request (Union[google.cloud.clouddms_v1.types.CreateConnectionProfileRequest, dict]):
                 The request object. Request message for
                 'CreateConnectionProfile' request.
             parent (:class:`str`):
@@ -1304,11 +1306,11 @@ async def create_connection_profile(
 
     async def update_connection_profile(
         self,
-        request: clouddms.UpdateConnectionProfileRequest = None,
+        request: Union[clouddms.UpdateConnectionProfileRequest, dict] = None,
         *,
         connection_profile: clouddms_resources.ConnectionProfile = None,
         update_mask: field_mask_pb2.FieldMask = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> operation_async.AsyncOperation:
@@ -1316,7 +1318,7 @@ async def update_connection_profile(
         profile.
 
         Args:
-            request (:class:`google.cloud.clouddms_v1.types.UpdateConnectionProfileRequest`):
+            request (Union[google.cloud.clouddms_v1.types.UpdateConnectionProfileRequest, dict]):
                 The request object. Request message for
                 'UpdateConnectionProfile' request.
             connection_profile (:class:`google.cloud.clouddms_v1.types.ConnectionProfile`):
@@ -1401,10 +1403,10 @@ async def update_connection_profile(
 
     async def delete_connection_profile(
         self,
-        request: clouddms.DeleteConnectionProfileRequest = None,
+        request: Union[clouddms.DeleteConnectionProfileRequest, dict] = None,
         *,
         name: str = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> operation_async.AsyncOperation:
@@ -1414,7 +1416,7 @@ async def delete_connection_profile(
         jobs.
 
         Args:
-            request (:class:`google.cloud.clouddms_v1.types.DeleteConnectionProfileRequest`):
+            request (Union[google.cloud.clouddms_v1.types.DeleteConnectionProfileRequest, dict]):
                 The request object. Request message for
                 'DeleteConnectionProfile' request.
             name (:class:`str`):
diff --git a/google/cloud/clouddms_v1/services/data_migration_service/client.py b/google/cloud/clouddms_v1/services/data_migration_service/client.py
index 898ecac..0664e87 100644
--- a/google/cloud/clouddms_v1/services/data_migration_service/client.py
+++ b/google/cloud/clouddms_v1/services/data_migration_service/client.py
@@ -30,6 +30,8 @@
 from google.auth.exceptions import MutualTLSChannelError  # type: ignore
 from google.oauth2 import service_account  # type: ignore
 
+OptionalRetry = Union[retries.Retry, object]
+
 from google.api_core import operation  # type: ignore
 from google.api_core import operation_async  # type: ignore
 from google.cloud.clouddms_v1.services.data_migration_service import pagers
@@ -380,7 +382,7 @@ def list_migration_jobs(
         request: Union[clouddms.ListMigrationJobsRequest, dict] = None,
         *,
         parent: str = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> pagers.ListMigrationJobsPager:
@@ -460,7 +462,7 @@ def get_migration_job(
         request: Union[clouddms.GetMigrationJobRequest, dict] = None,
         *,
         name: str = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> clouddms_resources.MigrationJob:
@@ -533,7 +535,7 @@ def create_migration_job(
         parent: str = None,
         migration_job: clouddms_resources.MigrationJob = None,
         migration_job_id: str = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> operation.Operation:
@@ -638,7 +640,7 @@ def update_migration_job(
         *,
         migration_job: clouddms_resources.MigrationJob = None,
         update_mask: field_mask_pb2.FieldMask = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> operation.Operation:
@@ -734,7 +736,7 @@ def delete_migration_job(
         request: Union[clouddms.DeleteMigrationJobRequest, dict] = None,
         *,
         name: str = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> operation.Operation:
@@ -825,7 +827,7 @@ def start_migration_job(
         self,
         request: Union[clouddms.StartMigrationJobRequest, dict] = None,
         *,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> operation.Operation:
@@ -887,7 +889,7 @@ def stop_migration_job(
         self,
         request: Union[clouddms.StopMigrationJobRequest, dict] = None,
         *,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> operation.Operation:
@@ -949,7 +951,7 @@ def resume_migration_job(
         self,
         request: Union[clouddms.ResumeMigrationJobRequest, dict] = None,
         *,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> operation.Operation:
@@ -1012,7 +1014,7 @@ def promote_migration_job(
         self,
         request: Union[clouddms.PromoteMigrationJobRequest, dict] = None,
         *,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> operation.Operation:
@@ -1076,7 +1078,7 @@ def verify_migration_job(
         self,
         request: Union[clouddms.VerifyMigrationJobRequest, dict] = None,
         *,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> operation.Operation:
@@ -1140,7 +1142,7 @@ def restart_migration_job(
         self,
         request: Union[clouddms.RestartMigrationJobRequest, dict] = None,
         *,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> operation.Operation:
@@ -1204,7 +1206,7 @@ def generate_ssh_script(
         self,
         request: Union[clouddms.GenerateSshScriptRequest, dict] = None,
         *,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> clouddms.SshScript:
@@ -1258,7 +1260,7 @@ def list_connection_profiles(
         request: Union[clouddms.ListConnectionProfilesRequest, dict] = None,
         *,
         parent: str = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> pagers.ListConnectionProfilesPager:
@@ -1339,7 +1341,7 @@ def get_connection_profile(
         request: Union[clouddms.GetConnectionProfileRequest, dict] = None,
         *,
         name: str = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> clouddms_resources.ConnectionProfile:
@@ -1410,7 +1412,7 @@ def create_connection_profile(
         parent: str = None,
         connection_profile: clouddms_resources.ConnectionProfile = None,
         connection_profile_id: str = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> operation.Operation:
@@ -1514,7 +1516,7 @@ def update_connection_profile(
         *,
         connection_profile: clouddms_resources.ConnectionProfile = None,
         update_mask: field_mask_pb2.FieldMask = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> operation.Operation:
@@ -1612,7 +1614,7 @@ def delete_connection_profile(
         request: Union[clouddms.DeleteConnectionProfileRequest, dict] = None,
         *,
         name: str = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> operation.Operation:
diff --git a/google/cloud/clouddms_v1/services/data_migration_service/transports/base.py b/google/cloud/clouddms_v1/services/data_migration_service/transports/base.py
index 892cfc9..639e3f1 100644
--- a/google/cloud/clouddms_v1/services/data_migration_service/transports/base.py
+++ b/google/cloud/clouddms_v1/services/data_migration_service/transports/base.py
@@ -15,7 +15,6 @@
 #
 import abc
 from typing import Awaitable, Callable, Dict, Optional, Sequence, Union
-import packaging.version
 import pkg_resources
 
 import google.auth  # type: ignore
@@ -38,15 +37,6 @@
 except pkg_resources.DistributionNotFound:
     DEFAULT_CLIENT_INFO = gapic_v1.client_info.ClientInfo()
 
-try:
-    # google.auth.__version__ was added in 1.26.0
-    _GOOGLE_AUTH_VERSION = google.auth.__version__
-except AttributeError:
-    try:  # try pkg_resources if it is available
-        _GOOGLE_AUTH_VERSION = pkg_resources.get_distribution("google-auth").version
-    except pkg_resources.DistributionNotFound:  # pragma: NO COVER
-        _GOOGLE_AUTH_VERSION = None
-
 
 class DataMigrationServiceTransport(abc.ABC):
     """Abstract transport class for DataMigrationService."""
@@ -96,7 +86,7 @@ def __init__(
             host += ":443"
         self._host = host
 
-        scopes_kwargs = self._get_scopes_kwargs(self._host, scopes)
+        scopes_kwargs = {"scopes": scopes, "default_scopes": self.AUTH_SCOPES}
 
         # Save the scopes.
         self._scopes = scopes
@@ -129,29 +119,6 @@ def __init__(
         # Save the credentials.
         self._credentials = credentials
 
-    # TODO(busunkim): This method is in the base transport
-    # to avoid duplicating code across the transport classes. These functions
-    # should be deleted once the minimum required versions of google-auth is increased.
-
-    # TODO: Remove this function once google-auth >= 1.25.0 is required
-    @classmethod
-    def _get_scopes_kwargs(
-        cls, host: str, scopes: Optional[Sequence[str]]
-    ) -> Dict[str, Optional[Sequence[str]]]:
-        """Returns scopes kwargs to pass to google-auth methods depending on the google-auth version"""
-
-        scopes_kwargs = {}
-
-        if _GOOGLE_AUTH_VERSION and (
-            packaging.version.parse(_GOOGLE_AUTH_VERSION)
-            >= packaging.version.parse("1.25.0")
-        ):
-            scopes_kwargs = {"scopes": scopes, "default_scopes": cls.AUTH_SCOPES}
-        else:
-            scopes_kwargs = {"scopes": scopes or cls.AUTH_SCOPES}
-
-        return scopes_kwargs
-
     def _prep_wrapped_messages(self, client_info):
         # Precompute the wrapped methods.
         self._wrapped_methods = {
@@ -242,7 +209,7 @@ def close(self):
         raise NotImplementedError()
 
     @property
-    def operations_client(self) -> operations_v1.OperationsClient:
+    def operations_client(self):
         """Return the client designed to process long-running operations."""
         raise NotImplementedError()
 
diff --git a/google/cloud/clouddms_v1/services/data_migration_service/transports/grpc.py b/google/cloud/clouddms_v1/services/data_migration_service/transports/grpc.py
index fae8123..f837ec7 100644
--- a/google/cloud/clouddms_v1/services/data_migration_service/transports/grpc.py
+++ b/google/cloud/clouddms_v1/services/data_migration_service/transports/grpc.py
@@ -113,7 +113,7 @@ def __init__(
         self._grpc_channel = None
         self._ssl_channel_credentials = ssl_channel_credentials
         self._stubs: Dict[str, Callable] = {}
-        self._operations_client = None
+        self._operations_client: Optional[operations_v1.OperationsClient] = None
 
         if api_mtls_endpoint:
             warnings.warn("api_mtls_endpoint is deprecated", DeprecationWarning)
diff --git a/google/cloud/clouddms_v1/services/data_migration_service/transports/grpc_asyncio.py b/google/cloud/clouddms_v1/services/data_migration_service/transports/grpc_asyncio.py
index 7f2cd57..e9d9025 100644
--- a/google/cloud/clouddms_v1/services/data_migration_service/transports/grpc_asyncio.py
+++ b/google/cloud/clouddms_v1/services/data_migration_service/transports/grpc_asyncio.py
@@ -21,7 +21,6 @@
 from google.api_core import operations_v1  # type: ignore
 from google.auth import credentials as ga_credentials  # type: ignore
 from google.auth.transport.grpc import SslCredentials  # type: ignore
-import packaging.version
 
 import grpc  # type: ignore
 from grpc.experimental import aio  # type: ignore
@@ -160,7 +159,7 @@ def __init__(
         self._grpc_channel = None
         self._ssl_channel_credentials = ssl_channel_credentials
         self._stubs: Dict[str, Callable] = {}
-        self._operations_client = None
+        self._operations_client: Optional[operations_v1.OperationsAsyncClient] = None
 
         if api_mtls_endpoint:
             warnings.warn("api_mtls_endpoint is deprecated", DeprecationWarning)
diff --git a/google/cloud/clouddms_v1/types/clouddms.py b/google/cloud/clouddms_v1/types/clouddms.py
index f41582c..4410443 100644
--- a/google/cloud/clouddms_v1/types/clouddms.py
+++ b/google/cloud/clouddms_v1/types/clouddms.py
@@ -301,6 +301,13 @@ class RestartMigrationJobRequest(proto.Message):
 class GenerateSshScriptRequest(proto.Message):
     r"""Request message for 'GenerateSshScript' request.
 
+    This message has `oneof`_ fields (mutually exclusive fields).
+    For each oneof, at most one member field can be set at the same time.
+    Setting any member of the oneof automatically clears all other
+    members.
+
+    .. _oneof: https://proto-plus-python.readthedocs.io/en/stable/fields.html#oneofs-mutually-exclusive-fields
+
     Attributes:
         migration_job (str):
             Name of the migration job resource to
@@ -310,8 +317,10 @@ class GenerateSshScriptRequest(proto.Message):
             to create.
         vm_creation_config (google.cloud.clouddms_v1.types.VmCreationConfig):
             The VM creation configuration
+            This field is a member of `oneof`_ ``vm_config``.
         vm_selection_config (google.cloud.clouddms_v1.types.VmSelectionConfig):
             The VM selection configuration
+            This field is a member of `oneof`_ ``vm_config``.
         vm_port (int):
             The port that will be open on the bastion
             host
diff --git a/google/cloud/clouddms_v1/types/clouddms_resources.py b/google/cloud/clouddms_v1/types/clouddms_resources.py
index 4989041..d6982b6 100644
--- a/google/cloud/clouddms_v1/types/clouddms_resources.py
+++ b/google/cloud/clouddms_v1/types/clouddms_resources.py
@@ -212,6 +212,13 @@ class CloudSqlConnectionProfile(proto.Message):
 class SqlAclEntry(proto.Message):
     r"""An entry for an Access Control list.
 
+    This message has `oneof`_ fields (mutually exclusive fields).
+    For each oneof, at most one member field can be set at the same time.
+    Setting any member of the oneof automatically clears all other
+    members.
+
+    .. _oneof: https://proto-plus-python.readthedocs.io/en/stable/fields.html#oneofs-mutually-exclusive-fields
+
     Attributes:
         value (str):
             The allowlisted value for the access control
@@ -220,9 +227,11 @@ class SqlAclEntry(proto.Message):
             The time when this access control entry expires in `RFC
             3339 <https://tools.ietf.org/html/rfc3339>`__ format, for
             example: ``2012-11-15T16:19:00.094Z``.
+            This field is a member of `oneof`_ ``expiration``.
         ttl (google.protobuf.duration_pb2.Duration):
             Input only. The time-to-leave of this access
             control entry.
+            This field is a member of `oneof`_ ``expiration``.
         label (str):
             A label to identify this entry.
     """
@@ -464,6 +473,13 @@ class DatabaseType(proto.Message):
 class MigrationJob(proto.Message):
     r"""Represents a Database Migration Service migration job object.
 
+    This message has `oneof`_ fields (mutually exclusive fields).
+    For each oneof, at most one member field can be set at the same time.
+    Setting any member of the oneof automatically clears all other
+    members.
+
+    .. _oneof: https://proto-plus-python.readthedocs.io/en/stable/fields.html#oneofs-mutually-exclusive-fields
+
     Attributes:
         name (str):
             The name (URI) of this migration job
@@ -507,12 +523,15 @@ class MigrationJob(proto.Message):
         reverse_ssh_connectivity (google.cloud.clouddms_v1.types.ReverseSshConnectivity):
             The details needed to communicate to the
             source over Reverse SSH tunnel connectivity.
+            This field is a member of `oneof`_ ``connectivity``.
         vpc_peering_connectivity (google.cloud.clouddms_v1.types.VpcPeeringConnectivity):
             The details of the VPC network that the
             source database is located in.
+            This field is a member of `oneof`_ ``connectivity``.
         static_ip_connectivity (google.cloud.clouddms_v1.types.StaticIpConnectivity):
             static ip connectivity data (default, no
             additional details needed).
+            This field is a member of `oneof`_ ``connectivity``.
         duration (google.protobuf.duration_pb2.Duration):
             Output only. The duration of the migration
             job (in seconds). A duration in seconds with up
@@ -604,6 +623,13 @@ class Type(proto.Enum):
 class ConnectionProfile(proto.Message):
     r"""A connection profile definition.
 
+    This message has `oneof`_ fields (mutually exclusive fields).
+    For each oneof, at most one member field can be set at the same time.
+    Setting any member of the oneof automatically clears all other
+    members.
+
+    .. _oneof: https://proto-plus-python.readthedocs.io/en/stable/fields.html#oneofs-mutually-exclusive-fields
+
     Attributes:
         name (str):
             The name of this connection profile resource
@@ -634,10 +660,13 @@ class ConnectionProfile(proto.Message):
             The connection profile display name.
         mysql (google.cloud.clouddms_v1.types.MySqlConnectionProfile):
             A MySQL database connection profile.
+            This field is a member of `oneof`_ ``connection_profile``.
         postgresql (google.cloud.clouddms_v1.types.PostgreSqlConnectionProfile):
             A PostgreSQL database connection profile.
+            This field is a member of `oneof`_ ``connection_profile``.
         cloudsql (google.cloud.clouddms_v1.types.CloudSqlConnectionProfile):
             A CloudSQL database connection profile.
+            This field is a member of `oneof`_ ``connection_profile``.
         error (google.rpc.status_pb2.Status):
             Output only. The error details in case of
             state FAILED.
diff --git a/setup.py b/setup.py
index 06679e3..40299fa 100644
--- a/setup.py
+++ b/setup.py
@@ -29,9 +29,8 @@
     # NOTE: Maintainers, please do not require google-api-core>=2.x.x
     # Until this issue is closed
     # https://github.com/googleapis/google-cloud-python/issues/10566
-    "google-api-core[grpc] >= 1.26.0, <3.0.0dev",
+    "google-api-core[grpc] >= 1.28.0, <3.0.0dev",
     "proto-plus >= 1.15.0",
-    "packaging >= 14.3",
 ]
 
 package_root = os.path.abspath(os.path.dirname(__file__))
diff --git a/testing/constraints-3.6.txt b/testing/constraints-3.6.txt
index fe11de2..1e3ec8b 100644
--- a/testing/constraints-3.6.txt
+++ b/testing/constraints-3.6.txt
@@ -4,7 +4,5 @@
 # Pin the version to the lower bound.
 # e.g., if setup.py has "google-cloud-foo >= 1.14.0, < 2.0.0dev",
 # Then this file should have google-cloud-foo==1.14.0
-google-api-core==1.26.0
+google-api-core==1.28.0
 proto-plus==1.15.0
-packaging==14.3
-google-auth==1.24.0  # TODO: remove when google-auth>=1.25.0 si transitively required through google-api-core
\ No newline at end of file
diff --git a/tests/unit/gapic/clouddms_v1/test_data_migration_service.py b/tests/unit/gapic/clouddms_v1/test_data_migration_service.py
index dc2c1b1..9291ff1 100644
--- a/tests/unit/gapic/clouddms_v1/test_data_migration_service.py
+++ b/tests/unit/gapic/clouddms_v1/test_data_migration_service.py
@@ -15,7 +15,6 @@
 #
 import os
 import mock
-import packaging.version
 
 import grpc
 from grpc.experimental import aio
@@ -43,9 +42,6 @@
 )
 from google.cloud.clouddms_v1.services.data_migration_service import pagers
 from google.cloud.clouddms_v1.services.data_migration_service import transports
-from google.cloud.clouddms_v1.services.data_migration_service.transports.base import (
-    _GOOGLE_AUTH_VERSION,
-)
 from google.cloud.clouddms_v1.types import clouddms
 from google.cloud.clouddms_v1.types import clouddms_resources
 from google.longrunning import operations_pb2
@@ -59,20 +55,6 @@
 import google.auth
 
 
-# TODO(busunkim): Once google-auth >= 1.25.0 is required transitively
-# through google-api-core:
-# - Delete the auth "less than" test cases
-# - Delete these pytest markers (Make the "greater than or equal to" tests the default).
-requires_google_auth_lt_1_25_0 = pytest.mark.skipif(
-    packaging.version.parse(_GOOGLE_AUTH_VERSION) >= packaging.version.parse("1.25.0"),
-    reason="This test requires google-auth < 1.25.0",
-)
-requires_google_auth_gte_1_25_0 = pytest.mark.skipif(
-    packaging.version.parse(_GOOGLE_AUTH_VERSION) < packaging.version.parse("1.25.0"),
-    reason="This test requires google-auth >= 1.25.0",
-)
-
-
 def client_cert_source_callback():
     return b"cert bytes", b"key bytes"
 
@@ -234,7 +216,7 @@ def test_data_migration_service_client_client_options(
     options = client_options.ClientOptions(api_endpoint="squid.clam.whelk")
     with mock.patch.object(transport_class, "__init__") as patched:
         patched.return_value = None
-        client = client_class(client_options=options)
+        client = client_class(transport=transport_name, client_options=options)
         patched.assert_called_once_with(
             credentials=None,
             credentials_file=None,
@@ -251,7 +233,7 @@ def test_data_migration_service_client_client_options(
     with mock.patch.dict(os.environ, {"GOOGLE_API_USE_MTLS_ENDPOINT": "never"}):
         with mock.patch.object(transport_class, "__init__") as patched:
             patched.return_value = None
-            client = client_class()
+            client = client_class(transport=transport_name)
             patched.assert_called_once_with(
                 credentials=None,
                 credentials_file=None,
@@ -268,7 +250,7 @@ def test_data_migration_service_client_client_options(
     with mock.patch.dict(os.environ, {"GOOGLE_API_USE_MTLS_ENDPOINT": "always"}):
         with mock.patch.object(transport_class, "__init__") as patched:
             patched.return_value = None
-            client = client_class()
+            client = client_class(transport=transport_name)
             patched.assert_called_once_with(
                 credentials=None,
                 credentials_file=None,
@@ -297,7 +279,7 @@ def test_data_migration_service_client_client_options(
     options = client_options.ClientOptions(quota_project_id="octopus")
     with mock.patch.object(transport_class, "__init__") as patched:
         patched.return_value = None
-        client = client_class(client_options=options)
+        client = client_class(transport=transport_name, client_options=options)
         patched.assert_called_once_with(
             credentials=None,
             credentials_file=None,
@@ -366,7 +348,7 @@ def test_data_migration_service_client_mtls_env_auto(
         )
         with mock.patch.object(transport_class, "__init__") as patched:
             patched.return_value = None
-            client = client_class(client_options=options)
+            client = client_class(transport=transport_name, client_options=options)
 
             if use_client_cert_env == "false":
                 expected_client_cert_source = None
@@ -408,7 +390,7 @@ def test_data_migration_service_client_mtls_env_auto(
                         expected_client_cert_source = client_cert_source_callback
 
                     patched.return_value = None
-                    client = client_class()
+                    client = client_class(transport=transport_name)
                     patched.assert_called_once_with(
                         credentials=None,
                         credentials_file=None,
@@ -430,7 +412,7 @@ def test_data_migration_service_client_mtls_env_auto(
                 return_value=False,
             ):
                 patched.return_value = None
-                client = client_class()
+                client = client_class(transport=transport_name)
                 patched.assert_called_once_with(
                     credentials=None,
                     credentials_file=None,
@@ -465,7 +447,7 @@ def test_data_migration_service_client_client_options_scopes(
     options = client_options.ClientOptions(scopes=["1", "2"],)
     with mock.patch.object(transport_class, "__init__") as patched:
         patched.return_value = None
-        client = client_class(client_options=options)
+        client = client_class(transport=transport_name, client_options=options)
         patched.assert_called_once_with(
             credentials=None,
             credentials_file=None,
@@ -500,7 +482,7 @@ def test_data_migration_service_client_client_options_credentials_file(
     options = client_options.ClientOptions(credentials_file="credentials.json")
     with mock.patch.object(transport_class, "__init__") as patched:
         patched.return_value = None
-        client = client_class(client_options=options)
+        client = client_class(transport=transport_name, client_options=options)
         patched.assert_called_once_with(
             credentials=None,
             credentials_file="credentials.json",
@@ -4398,7 +4380,6 @@ def test_data_migration_service_base_transport():
         transport.operations_client
 
 
-@requires_google_auth_gte_1_25_0
 def test_data_migration_service_base_transport_with_credentials_file():
     # Instantiate the base transport with a credentials file
     with mock.patch.object(
@@ -4419,26 +4400,6 @@ def test_data_migration_service_base_transport_with_credentials_file():
         )
 
 
-@requires_google_auth_lt_1_25_0
-def test_data_migration_service_base_transport_with_credentials_file_old_google_auth():
-    # Instantiate the base transport with a credentials file
-    with mock.patch.object(
-        google.auth, "load_credentials_from_file", autospec=True
-    ) as load_creds, mock.patch(
-        "google.cloud.clouddms_v1.services.data_migration_service.transports.DataMigrationServiceTransport._prep_wrapped_messages"
-    ) as Transport:
-        Transport.return_value = None
-        load_creds.return_value = (ga_credentials.AnonymousCredentials(), None)
-        transport = transports.DataMigrationServiceTransport(
-            credentials_file="credentials.json", quota_project_id="octopus",
-        )
-        load_creds.assert_called_once_with(
-            "credentials.json",
-            scopes=("https://www.googleapis.com/auth/cloud-platform",),
-            quota_project_id="octopus",
-        )
-
-
 def test_data_migration_service_base_transport_with_adc():
     # Test the default credentials are used if credentials and credentials_file are None.
     with mock.patch.object(google.auth, "default", autospec=True) as adc, mock.patch(
@@ -4450,7 +4411,6 @@ def test_data_migration_service_base_transport_with_adc():
         adc.assert_called_once()
 
 
-@requires_google_auth_gte_1_25_0
 def test_data_migration_service_auth_adc():
     # If no credentials are provided, we should use ADC credentials.
     with mock.patch.object(google.auth, "default", autospec=True) as adc:
@@ -4463,18 +4423,6 @@ def test_data_migration_service_auth_adc():
         )
 
 
-@requires_google_auth_lt_1_25_0
-def test_data_migration_service_auth_adc_old_google_auth():
-    # If no credentials are provided, we should use ADC credentials.
-    with mock.patch.object(google.auth, "default", autospec=True) as adc:
-        adc.return_value = (ga_credentials.AnonymousCredentials(), None)
-        DataMigrationServiceClient()
-        adc.assert_called_once_with(
-            scopes=("https://www.googleapis.com/auth/cloud-platform",),
-            quota_project_id=None,
-        )
-
-
 @pytest.mark.parametrize(
     "transport_class",
     [
@@ -4482,7 +4430,6 @@ def test_data_migration_service_auth_adc_old_google_auth():
         transports.DataMigrationServiceGrpcAsyncIOTransport,
     ],
 )
-@requires_google_auth_gte_1_25_0
 def test_data_migration_service_transport_auth_adc(transport_class):
     # If credentials and host are not provided, the transport class should use
     # ADC credentials.
@@ -4496,26 +4443,6 @@ def test_data_migration_service_transport_auth_adc(transport_class):
         )
 
 
-@pytest.mark.parametrize(
-    "transport_class",
-    [
-        transports.DataMigrationServiceGrpcTransport,
-        transports.DataMigrationServiceGrpcAsyncIOTransport,
-    ],
-)
-@requires_google_auth_lt_1_25_0
-def test_data_migration_service_transport_auth_adc_old_google_auth(transport_class):
-    # If credentials and host are not provided, the transport class should use
-    # ADC credentials.
-    with mock.patch.object(google.auth, "default", autospec=True) as adc:
-        adc.return_value = (ga_credentials.AnonymousCredentials(), None)
-        transport_class(quota_project_id="octopus")
-        adc.assert_called_once_with(
-            scopes=("https://www.googleapis.com/auth/cloud-platform",),
-            quota_project_id="octopus",
-        )
-
-
 @pytest.mark.parametrize(
     "transport_class,grpc_helpers",
     [