diff --git a/.github/.OwlBot.lock.yaml b/.github/.OwlBot.lock.yaml
new file mode 100644
index 00000000..9bdafee7
--- /dev/null
+++ b/.github/.OwlBot.lock.yaml
@@ -0,0 +1,4 @@
+docker:
+  digest: sha256:612842ba5ccf62b4e3983fe6dc453cf66883c74bc168aa62da7acaed1e2fdc93
+  image: gcr.io/repo-automation-bots/owlbot-python:latest  
+
diff --git a/.github/.OwlBot.yaml b/.github/.OwlBot.yaml
new file mode 100644
index 00000000..99839dbe
--- /dev/null
+++ b/.github/.OwlBot.yaml
@@ -0,0 +1,26 @@
+# 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
+#
+#     http://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.
+
+docker:
+  image: gcr.io/repo-automation-bots/owlbot-python:latest
+
+deep-remove-regex:
+  - /owl-bot-staging
+
+deep-copy-regex:
+  - source: /google/cloud/bigquery/datatransfer/(v.*)/.*-py/(.*)
+    dest: /owl-bot-staging/$1/$2
+
+begin-after-commit-hash: ad5147b2c3694044935301527f68b951c2e1f419
+
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index a9024b15..32302e48 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -12,6 +12,6 @@ repos:
     hooks:
     - id: black
 -   repo: https://gitlab.com/pycqa/flake8
-    rev: 3.8.4
+    rev: 3.9.0
     hooks:
     - id: flake8
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 469b8f37..460c160d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,14 @@
 
 [1]: https://pypi.org/project/google-cloud-bigquery-datatransfer/#history
 
+### [3.1.1](https://www.github.com/googleapis/python-bigquery-datatransfer/compare/v3.1.0...v3.1.1) (2021-04-07)
+
+
+### Bug Fixes
+
+* require proto-plus>=1.15.0 ([91910f1](https://www.github.com/googleapis/python-bigquery-datatransfer/commit/91910f1ea01c5324fa63a7d85a034d08aeaae3f9))
+* use correct retry deadline ([#121](https://www.github.com/googleapis/python-bigquery-datatransfer/issues/121)) ([91910f1](https://www.github.com/googleapis/python-bigquery-datatransfer/commit/91910f1ea01c5324fa63a7d85a034d08aeaae3f9))
+
 ## [3.1.0](https://www.github.com/googleapis/python-bigquery-datatransfer/compare/v3.0.1...v3.1.0) (2021-03-22)
 
 
diff --git a/UPGRADING.md b/UPGRADING.md
index 0bac7ed1..b9e04ba1 100644
--- a/UPGRADING.md
+++ b/UPGRADING.md
@@ -1,4 +1,4 @@
-<!-- 
+<!--
 Copyright 2020 Google LLC
 
 Licensed under the Apache License, Version 2.0 (the "License");
@@ -80,7 +80,7 @@ that will convert most common use cases.
 * Install the library
 
 ```py
-python3 -m pip install google-cloud-bigquery-datatransfer
+python3 -m pip install google-cloud-bigquery-datatransfer[libcst]
 ```
 
 * The script `fixup_datatransfer_v1_keywords.py` is shipped with the library. It expects
diff --git a/google/cloud/bigquery_datatransfer_v1/services/data_transfer_service/async_client.py b/google/cloud/bigquery_datatransfer_v1/services/data_transfer_service/async_client.py
index e70d43e3..47ac9f6d 100644
--- a/google/cloud/bigquery_datatransfer_v1/services/data_transfer_service/async_client.py
+++ b/google/cloud/bigquery_datatransfer_v1/services/data_transfer_service/async_client.py
@@ -256,6 +256,7 @@ async def get_data_source(
                 predicate=retries.if_exception_type(
                     exceptions.DeadlineExceeded, exceptions.ServiceUnavailable,
                 ),
+                deadline=20.0,
             ),
             default_timeout=20.0,
             client_info=DEFAULT_CLIENT_INFO,
@@ -343,6 +344,7 @@ async def list_data_sources(
                 predicate=retries.if_exception_type(
                     exceptions.DeadlineExceeded, exceptions.ServiceUnavailable,
                 ),
+                deadline=20.0,
             ),
             default_timeout=20.0,
             client_info=DEFAULT_CLIENT_INFO,
@@ -621,6 +623,7 @@ async def delete_transfer_config(
                 predicate=retries.if_exception_type(
                     exceptions.DeadlineExceeded, exceptions.ServiceUnavailable,
                 ),
+                deadline=20.0,
             ),
             default_timeout=20.0,
             client_info=DEFAULT_CLIENT_INFO,
@@ -709,6 +712,7 @@ async def get_transfer_config(
                 predicate=retries.if_exception_type(
                     exceptions.DeadlineExceeded, exceptions.ServiceUnavailable,
                 ),
+                deadline=20.0,
             ),
             default_timeout=20.0,
             client_info=DEFAULT_CLIENT_INFO,
@@ -795,6 +799,7 @@ async def list_transfer_configs(
                 predicate=retries.if_exception_type(
                     exceptions.DeadlineExceeded, exceptions.ServiceUnavailable,
                 ),
+                deadline=20.0,
             ),
             default_timeout=20.0,
             client_info=DEFAULT_CLIENT_INFO,
@@ -1036,6 +1041,7 @@ async def get_transfer_run(
                 predicate=retries.if_exception_type(
                     exceptions.DeadlineExceeded, exceptions.ServiceUnavailable,
                 ),
+                deadline=20.0,
             ),
             default_timeout=20.0,
             client_info=DEFAULT_CLIENT_INFO,
@@ -1114,6 +1120,7 @@ async def delete_transfer_run(
                 predicate=retries.if_exception_type(
                     exceptions.DeadlineExceeded, exceptions.ServiceUnavailable,
                 ),
+                deadline=20.0,
             ),
             default_timeout=20.0,
             client_info=DEFAULT_CLIENT_INFO,
@@ -1202,6 +1209,7 @@ async def list_transfer_runs(
                 predicate=retries.if_exception_type(
                     exceptions.DeadlineExceeded, exceptions.ServiceUnavailable,
                 ),
+                deadline=20.0,
             ),
             default_timeout=20.0,
             client_info=DEFAULT_CLIENT_INFO,
@@ -1295,6 +1303,7 @@ async def list_transfer_logs(
                 predicate=retries.if_exception_type(
                     exceptions.DeadlineExceeded, exceptions.ServiceUnavailable,
                 ),
+                deadline=20.0,
             ),
             default_timeout=20.0,
             client_info=DEFAULT_CLIENT_INFO,
@@ -1396,6 +1405,7 @@ async def check_valid_creds(
                 predicate=retries.if_exception_type(
                     exceptions.DeadlineExceeded, exceptions.ServiceUnavailable,
                 ),
+                deadline=20.0,
             ),
             default_timeout=20.0,
             client_info=DEFAULT_CLIENT_INFO,
diff --git a/google/cloud/bigquery_datatransfer_v1/services/data_transfer_service/transports/base.py b/google/cloud/bigquery_datatransfer_v1/services/data_transfer_service/transports/base.py
index 3633ae8e..104b9bff 100644
--- a/google/cloud/bigquery_datatransfer_v1/services/data_transfer_service/transports/base.py
+++ b/google/cloud/bigquery_datatransfer_v1/services/data_transfer_service/transports/base.py
@@ -71,10 +71,10 @@ def __init__(
             scope (Optional[Sequence[str]]): A list of scopes.
             quota_project_id (Optional[str]): An optional project to use for billing
                 and quota.
-            client_info (google.api_core.gapic_v1.client_info.ClientInfo):	
-                The client info used to send a user-agent string along with	
-                API requests. If ``None``, then default info will be used.	
-                Generally, you only need to set this if you're developing	
+            client_info (google.api_core.gapic_v1.client_info.ClientInfo):
+                The client info used to send a user-agent string along with
+                API requests. If ``None``, then default info will be used.
+                Generally, you only need to set this if you're developing
                 your own client library.
         """
         # Save the hostname. Default to port 443 (HTTPS) if none is specified.
@@ -82,6 +82,9 @@ def __init__(
             host += ":443"
         self._host = host
 
+        # Save the scopes.
+        self._scopes = scopes or self.AUTH_SCOPES
+
         # If no credentials are provided, then determine the appropriate
         # defaults.
         if credentials and credentials_file:
@@ -91,20 +94,17 @@ def __init__(
 
         if credentials_file is not None:
             credentials, _ = auth.load_credentials_from_file(
-                credentials_file, scopes=scopes, quota_project_id=quota_project_id
+                credentials_file, scopes=self._scopes, quota_project_id=quota_project_id
             )
 
         elif credentials is None:
             credentials, _ = auth.default(
-                scopes=scopes, quota_project_id=quota_project_id
+                scopes=self._scopes, quota_project_id=quota_project_id
             )
 
         # Save the credentials.
         self._credentials = credentials
 
-        # Lifted into its own function so it can be stubbed out during tests.
-        self._prep_wrapped_messages(client_info)
-
     def _prep_wrapped_messages(self, client_info):
         # Precompute the wrapped methods.
         self._wrapped_methods = {
@@ -117,6 +117,7 @@ def _prep_wrapped_messages(self, client_info):
                     predicate=retries.if_exception_type(
                         exceptions.DeadlineExceeded, exceptions.ServiceUnavailable,
                     ),
+                    deadline=20.0,
                 ),
                 default_timeout=20.0,
                 client_info=client_info,
@@ -130,6 +131,7 @@ def _prep_wrapped_messages(self, client_info):
                     predicate=retries.if_exception_type(
                         exceptions.DeadlineExceeded, exceptions.ServiceUnavailable,
                     ),
+                    deadline=20.0,
                 ),
                 default_timeout=20.0,
                 client_info=client_info,
@@ -153,6 +155,7 @@ def _prep_wrapped_messages(self, client_info):
                     predicate=retries.if_exception_type(
                         exceptions.DeadlineExceeded, exceptions.ServiceUnavailable,
                     ),
+                    deadline=20.0,
                 ),
                 default_timeout=20.0,
                 client_info=client_info,
@@ -166,6 +169,7 @@ def _prep_wrapped_messages(self, client_info):
                     predicate=retries.if_exception_type(
                         exceptions.DeadlineExceeded, exceptions.ServiceUnavailable,
                     ),
+                    deadline=20.0,
                 ),
                 default_timeout=20.0,
                 client_info=client_info,
@@ -179,6 +183,7 @@ def _prep_wrapped_messages(self, client_info):
                     predicate=retries.if_exception_type(
                         exceptions.DeadlineExceeded, exceptions.ServiceUnavailable,
                     ),
+                    deadline=20.0,
                 ),
                 default_timeout=20.0,
                 client_info=client_info,
@@ -202,6 +207,7 @@ def _prep_wrapped_messages(self, client_info):
                     predicate=retries.if_exception_type(
                         exceptions.DeadlineExceeded, exceptions.ServiceUnavailable,
                     ),
+                    deadline=20.0,
                 ),
                 default_timeout=20.0,
                 client_info=client_info,
@@ -215,6 +221,7 @@ def _prep_wrapped_messages(self, client_info):
                     predicate=retries.if_exception_type(
                         exceptions.DeadlineExceeded, exceptions.ServiceUnavailable,
                     ),
+                    deadline=20.0,
                 ),
                 default_timeout=20.0,
                 client_info=client_info,
@@ -228,6 +235,7 @@ def _prep_wrapped_messages(self, client_info):
                     predicate=retries.if_exception_type(
                         exceptions.DeadlineExceeded, exceptions.ServiceUnavailable,
                     ),
+                    deadline=20.0,
                 ),
                 default_timeout=20.0,
                 client_info=client_info,
@@ -241,6 +249,7 @@ def _prep_wrapped_messages(self, client_info):
                     predicate=retries.if_exception_type(
                         exceptions.DeadlineExceeded, exceptions.ServiceUnavailable,
                     ),
+                    deadline=20.0,
                 ),
                 default_timeout=20.0,
                 client_info=client_info,
@@ -254,6 +263,7 @@ def _prep_wrapped_messages(self, client_info):
                     predicate=retries.if_exception_type(
                         exceptions.DeadlineExceeded, exceptions.ServiceUnavailable,
                     ),
+                    deadline=20.0,
                 ),
                 default_timeout=20.0,
                 client_info=client_info,
diff --git a/google/cloud/bigquery_datatransfer_v1/services/data_transfer_service/transports/grpc.py b/google/cloud/bigquery_datatransfer_v1/services/data_transfer_service/transports/grpc.py
index 1f613e03..c6c39bb4 100644
--- a/google/cloud/bigquery_datatransfer_v1/services/data_transfer_service/transports/grpc.py
+++ b/google/cloud/bigquery_datatransfer_v1/services/data_transfer_service/transports/grpc.py
@@ -111,7 +111,9 @@ def __init__(
           google.api_core.exceptions.DuplicateCredentialArgs: If both ``credentials``
               and ``credentials_file`` are passed.
         """
+        self._grpc_channel = None
         self._ssl_channel_credentials = ssl_channel_credentials
+        self._stubs: Dict[str, Callable] = {}
 
         if api_mtls_endpoint:
             warnings.warn("api_mtls_endpoint is deprecated", DeprecationWarning)
@@ -119,70 +121,50 @@ def __init__(
             warnings.warn("client_cert_source is deprecated", DeprecationWarning)
 
         if channel:
-            # Sanity check: Ensure that channel and credentials are not both
-            # provided.
+            # Ignore credentials if a channel was passed.
             credentials = False
-
             # If a channel was explicitly provided, set it.
             self._grpc_channel = channel
             self._ssl_channel_credentials = None
-        elif api_mtls_endpoint:
-            host = (
-                api_mtls_endpoint
-                if ":" in api_mtls_endpoint
-                else api_mtls_endpoint + ":443"
-            )
-
-            if credentials is None:
-                credentials, _ = auth.default(
-                    scopes=self.AUTH_SCOPES, quota_project_id=quota_project_id
-                )
-
-            # Create SSL credentials with client_cert_source or application
-            # default SSL credentials.
-            if client_cert_source:
-                cert, key = client_cert_source()
-                ssl_credentials = grpc.ssl_channel_credentials(
-                    certificate_chain=cert, private_key=key
-                )
-            else:
-                ssl_credentials = SslCredentials().ssl_credentials
 
-            # create a new channel. The provided one is ignored.
-            self._grpc_channel = type(self).create_channel(
-                host,
-                credentials=credentials,
-                credentials_file=credentials_file,
-                ssl_credentials=ssl_credentials,
-                scopes=scopes or self.AUTH_SCOPES,
-                quota_project_id=quota_project_id,
-                options=[
-                    ("grpc.max_send_message_length", -1),
-                    ("grpc.max_receive_message_length", -1),
-                ],
-            )
-            self._ssl_channel_credentials = ssl_credentials
         else:
-            host = host if ":" in host else host + ":443"
+            if api_mtls_endpoint:
+                host = api_mtls_endpoint
+
+                # Create SSL credentials with client_cert_source or application
+                # default SSL credentials.
+                if client_cert_source:
+                    cert, key = client_cert_source()
+                    self._ssl_channel_credentials = grpc.ssl_channel_credentials(
+                        certificate_chain=cert, private_key=key
+                    )
+                else:
+                    self._ssl_channel_credentials = SslCredentials().ssl_credentials
 
-            if credentials is None:
-                credentials, _ = auth.default(
-                    scopes=self.AUTH_SCOPES, quota_project_id=quota_project_id
-                )
+            else:
+                if client_cert_source_for_mtls and not ssl_channel_credentials:
+                    cert, key = client_cert_source_for_mtls()
+                    self._ssl_channel_credentials = grpc.ssl_channel_credentials(
+                        certificate_chain=cert, private_key=key
+                    )
 
-            if client_cert_source_for_mtls and not ssl_channel_credentials:
-                cert, key = client_cert_source_for_mtls()
-                self._ssl_channel_credentials = grpc.ssl_channel_credentials(
-                    certificate_chain=cert, private_key=key
-                )
+        # The base transport sets the host, credentials and scopes
+        super().__init__(
+            host=host,
+            credentials=credentials,
+            credentials_file=credentials_file,
+            scopes=scopes,
+            quota_project_id=quota_project_id,
+            client_info=client_info,
+        )
 
-            # create a new channel. The provided one is ignored.
+        if not self._grpc_channel:
             self._grpc_channel = type(self).create_channel(
-                host,
-                credentials=credentials,
+                self._host,
+                credentials=self._credentials,
                 credentials_file=credentials_file,
+                scopes=self._scopes,
                 ssl_credentials=self._ssl_channel_credentials,
-                scopes=scopes or self.AUTH_SCOPES,
                 quota_project_id=quota_project_id,
                 options=[
                     ("grpc.max_send_message_length", -1),
@@ -190,17 +172,8 @@ def __init__(
                 ],
             )
 
-        self._stubs = {}  # type: Dict[str, Callable]
-
-        # Run the base constructor.
-        super().__init__(
-            host=host,
-            credentials=credentials,
-            credentials_file=credentials_file,
-            scopes=scopes or self.AUTH_SCOPES,
-            quota_project_id=quota_project_id,
-            client_info=client_info,
-        )
+        # Wrap messages. This must be done after self._grpc_channel exists
+        self._prep_wrapped_messages(client_info)
 
     @classmethod
     def create_channel(
@@ -214,7 +187,7 @@ def create_channel(
     ) -> grpc.Channel:
         """Create and return a gRPC channel object.
         Args:
-            address (Optional[str]): The host for the channel to use.
+            host (Optional[str]): The host for the channel to use.
             credentials (Optional[~.Credentials]): The
                 authorization credentials to attach to requests. These
                 credentials identify this application to the service. If
diff --git a/google/cloud/bigquery_datatransfer_v1/services/data_transfer_service/transports/grpc_asyncio.py b/google/cloud/bigquery_datatransfer_v1/services/data_transfer_service/transports/grpc_asyncio.py
index cc4a7cce..00cb6fb6 100644
--- a/google/cloud/bigquery_datatransfer_v1/services/data_transfer_service/transports/grpc_asyncio.py
+++ b/google/cloud/bigquery_datatransfer_v1/services/data_transfer_service/transports/grpc_asyncio.py
@@ -66,7 +66,7 @@ def create_channel(
     ) -> aio.Channel:
         """Create and return a gRPC AsyncIO channel object.
         Args:
-            address (Optional[str]): The host for the channel to use.
+            host (Optional[str]): The host for the channel to use.
             credentials (Optional[~.Credentials]): The
                 authorization credentials to attach to requests. These
                 credentials identify this application to the service. If
@@ -144,10 +144,10 @@ def __init__(
                 ignored if ``channel`` or ``ssl_channel_credentials`` is provided.
             quota_project_id (Optional[str]): An optional project to use for billing
                 and quota.
-            client_info (google.api_core.gapic_v1.client_info.ClientInfo):	
-                The client info used to send a user-agent string along with	
-                API requests. If ``None``, then default info will be used.	
-                Generally, you only need to set this if you're developing	
+            client_info (google.api_core.gapic_v1.client_info.ClientInfo):
+                The client info used to send a user-agent string along with
+                API requests. If ``None``, then default info will be used.
+                Generally, you only need to set this if you're developing
                 your own client library.
 
         Raises:
@@ -156,7 +156,9 @@ def __init__(
           google.api_core.exceptions.DuplicateCredentialArgs: If both ``credentials``
               and ``credentials_file`` are passed.
         """
+        self._grpc_channel = None
         self._ssl_channel_credentials = ssl_channel_credentials
+        self._stubs: Dict[str, Callable] = {}
 
         if api_mtls_endpoint:
             warnings.warn("api_mtls_endpoint is deprecated", DeprecationWarning)
@@ -164,70 +166,50 @@ def __init__(
             warnings.warn("client_cert_source is deprecated", DeprecationWarning)
 
         if channel:
-            # Sanity check: Ensure that channel and credentials are not both
-            # provided.
+            # Ignore credentials if a channel was passed.
             credentials = False
-
             # If a channel was explicitly provided, set it.
             self._grpc_channel = channel
             self._ssl_channel_credentials = None
-        elif api_mtls_endpoint:
-            host = (
-                api_mtls_endpoint
-                if ":" in api_mtls_endpoint
-                else api_mtls_endpoint + ":443"
-            )
-
-            if credentials is None:
-                credentials, _ = auth.default(
-                    scopes=self.AUTH_SCOPES, quota_project_id=quota_project_id
-                )
-
-            # Create SSL credentials with client_cert_source or application
-            # default SSL credentials.
-            if client_cert_source:
-                cert, key = client_cert_source()
-                ssl_credentials = grpc.ssl_channel_credentials(
-                    certificate_chain=cert, private_key=key
-                )
-            else:
-                ssl_credentials = SslCredentials().ssl_credentials
 
-            # create a new channel. The provided one is ignored.
-            self._grpc_channel = type(self).create_channel(
-                host,
-                credentials=credentials,
-                credentials_file=credentials_file,
-                ssl_credentials=ssl_credentials,
-                scopes=scopes or self.AUTH_SCOPES,
-                quota_project_id=quota_project_id,
-                options=[
-                    ("grpc.max_send_message_length", -1),
-                    ("grpc.max_receive_message_length", -1),
-                ],
-            )
-            self._ssl_channel_credentials = ssl_credentials
         else:
-            host = host if ":" in host else host + ":443"
+            if api_mtls_endpoint:
+                host = api_mtls_endpoint
+
+                # Create SSL credentials with client_cert_source or application
+                # default SSL credentials.
+                if client_cert_source:
+                    cert, key = client_cert_source()
+                    self._ssl_channel_credentials = grpc.ssl_channel_credentials(
+                        certificate_chain=cert, private_key=key
+                    )
+                else:
+                    self._ssl_channel_credentials = SslCredentials().ssl_credentials
 
-            if credentials is None:
-                credentials, _ = auth.default(
-                    scopes=self.AUTH_SCOPES, quota_project_id=quota_project_id
-                )
+            else:
+                if client_cert_source_for_mtls and not ssl_channel_credentials:
+                    cert, key = client_cert_source_for_mtls()
+                    self._ssl_channel_credentials = grpc.ssl_channel_credentials(
+                        certificate_chain=cert, private_key=key
+                    )
 
-            if client_cert_source_for_mtls and not ssl_channel_credentials:
-                cert, key = client_cert_source_for_mtls()
-                self._ssl_channel_credentials = grpc.ssl_channel_credentials(
-                    certificate_chain=cert, private_key=key
-                )
+        # The base transport sets the host, credentials and scopes
+        super().__init__(
+            host=host,
+            credentials=credentials,
+            credentials_file=credentials_file,
+            scopes=scopes,
+            quota_project_id=quota_project_id,
+            client_info=client_info,
+        )
 
-            # create a new channel. The provided one is ignored.
+        if not self._grpc_channel:
             self._grpc_channel = type(self).create_channel(
-                host,
-                credentials=credentials,
+                self._host,
+                credentials=self._credentials,
                 credentials_file=credentials_file,
+                scopes=self._scopes,
                 ssl_credentials=self._ssl_channel_credentials,
-                scopes=scopes or self.AUTH_SCOPES,
                 quota_project_id=quota_project_id,
                 options=[
                     ("grpc.max_send_message_length", -1),
@@ -235,17 +217,8 @@ def __init__(
                 ],
             )
 
-        # Run the base constructor.
-        super().__init__(
-            host=host,
-            credentials=credentials,
-            credentials_file=credentials_file,
-            scopes=scopes or self.AUTH_SCOPES,
-            quota_project_id=quota_project_id,
-            client_info=client_info,
-        )
-
-        self._stubs = {}
+        # Wrap messages. This must be done after self._grpc_channel exists
+        self._prep_wrapped_messages(client_info)
 
     @property
     def grpc_channel(self) -> aio.Channel:
diff --git a/google/cloud/bigquery_datatransfer_v1/types/transfer.py b/google/cloud/bigquery_datatransfer_v1/types/transfer.py
index 58e7a5e6..63274fab 100644
--- a/google/cloud/bigquery_datatransfer_v1/types/transfer.py
+++ b/google/cloud/bigquery_datatransfer_v1/types/transfer.py
@@ -39,6 +39,7 @@
 
 class TransferType(proto.Enum):
     r"""DEPRECATED. Represents data transfer type."""
+    _pb_options = {"deprecated": True}
     TRANSFER_TYPE_UNSPECIFIED = 0
     BATCH = 1
     STREAMING = 2
diff --git a/noxfile.py b/noxfile.py
index d6d974c5..af50a606 100644
--- a/noxfile.py
+++ b/noxfile.py
@@ -18,6 +18,7 @@
 
 from __future__ import absolute_import
 import os
+import pathlib
 import shutil
 
 import nox
@@ -30,6 +31,8 @@
 SYSTEM_TEST_PYTHON_VERSIONS = ["3.8"]
 UNIT_TEST_PYTHON_VERSIONS = ["3.6", "3.7", "3.8", "3.9"]
 
+CURRENT_DIRECTORY = pathlib.Path(__file__).parent.absolute()
+
 # 'docfx' is excluded since it only needs to run in 'docs-presubmit'
 nox.options.sessions = [
     "unit",
@@ -84,13 +87,15 @@ def lint_setup_py(session):
 
 def default(session):
     # Install all test dependencies, then install this package in-place.
-    session.install("asyncmock", "pytest-asyncio")
 
-    session.install(
-        "mock", "pytest", "pytest-cov",
+    constraints_path = str(
+        CURRENT_DIRECTORY / "testing" / f"constraints-{session.python}.txt"
     )
+    session.install("asyncmock", "pytest-asyncio", "-c", constraints_path)
 
-    session.install("-e", ".")
+    session.install("mock", "pytest", "pytest-cov", "-c", constraints_path)
+
+    session.install("-e", ".", "-c", constraints_path)
 
     # Run py.test against the unit tests.
     session.run(
@@ -117,6 +122,9 @@ def unit(session):
 @nox.session(python=SYSTEM_TEST_PYTHON_VERSIONS)
 def system(session):
     """Run the system test suite."""
+    constraints_path = str(
+        CURRENT_DIRECTORY / "testing" / f"constraints-{session.python}.txt"
+    )
     system_test_path = os.path.join("tests", "system.py")
     system_test_folder_path = os.path.join("tests", "system")
 
@@ -141,10 +149,8 @@ def system(session):
 
     # Install all test dependencies, then install this package into the
     # virtualenv's dist-packages.
-    session.install(
-        "mock", "pytest", "google-cloud-testutils",
-    )
-    session.install("-e", ".")
+    session.install("mock", "pytest", "google-cloud-testutils", "-c", constraints_path)
+    session.install("-e", ".", "-c", constraints_path)
 
     # Run py.test against the system tests.
     if system_test_exists:
@@ -205,9 +211,7 @@ def docfx(session):
     """Build the docfx yaml files for this library."""
 
     session.install("-e", ".")
-    # sphinx-docfx-yaml supports up to sphinx version 1.5.5.
-    # https://github.com/docascode/sphinx-docfx-yaml/issues/97
-    session.install("sphinx==1.5.5", "alabaster", "recommonmark", "sphinx-docfx-yaml")
+    session.install("sphinx", "alabaster", "recommonmark", "gcp-sphinx-docfx-yaml")
 
     shutil.rmtree(os.path.join("docs", "_build"), ignore_errors=True)
     session.run(
diff --git a/synth.py b/owlbot.py
similarity index 66%
rename from synth.py
rename to owlbot.py
index f5e03032..87e7c517 100644
--- a/synth.py
+++ b/owlbot.py
@@ -20,25 +20,29 @@
 from synthtool.languages import python
 
 
-gapic = gcp.GAPICBazel()
 common = gcp.CommonTemplates()
-versions = ["v1"]
 
 # ----------------------------------------------------------------------------
 # Generate bigquery_datatransfer GAPIC layer
 # ----------------------------------------------------------------------------
-for version in versions:
-    library = gapic.py_library(
-        service="bigquery_datatransfer",
-        version=version,
-        bazel_target=(
-            f"//google/cloud/bigquery/datatransfer/{version}:"
-            "bigquery-datatransfer-v1-py"
-        ),
-        include_protos=True,
+for library in s.get_staging_dirs("v1"):
+    # Fix missing async client in datatransfer_v1
+    # https://github.com/googleapis/gapic-generator-python/issues/815
+    s.replace(
+        library / "google/cloud/bigquery_datatransfer_v1/__init__.py",
+        r"from \.services\.data_transfer_service import DataTransferServiceClient",
+        "\\g<0>\nfrom .services.data_transfer_service import DataTransferServiceAsyncClient",
     )
+    s.replace(
+        library / "google/cloud/bigquery_datatransfer_v1/__init__.py",
+        r"'DataTransferServiceClient',",
+        '\\g<0>\n    "DataTransferServiceAsyncClient"',
+    )
+
     s.move(library, excludes=["*.tar.gz", "docs/index.rst", "README.rst", "setup.py"])
 
+s.remove_staging_dirs()
+
 
 # ----------------------------------------------------------------------------
 # Add templated files
@@ -52,17 +56,4 @@
 
 python.py_samples(skip_readmes=True)
 
-# Fix missing async client in datatransfer_v1
-# https://github.com/googleapis/gapic-generator-python/issues/815
-s.replace(
-    "google/cloud/bigquery_datatransfer_v1/__init__.py",
-    r"from \.services\.data_transfer_service import DataTransferServiceClient",
-    "\\g<0>\nfrom .services.data_transfer_service import DataTransferServiceAsyncClient",
-)
-s.replace(
-    "google/cloud/bigquery_datatransfer_v1/__init__.py",
-    r"'DataTransferServiceClient',",
-    '\\g<0>\n    "DataTransferServiceAsyncClient"',
-)
-
 s.shell.run(["nox", "-s", "blacken"], hide_output=False)
diff --git a/samples/snippets/requirements.txt b/samples/snippets/requirements.txt
index 93a5405d..e7fe546c 100644
--- a/samples/snippets/requirements.txt
+++ b/samples/snippets/requirements.txt
@@ -1 +1 @@
-google-cloud-bigquery-datatransfer==3.0.1
+google-cloud-bigquery-datatransfer==3.1.0
diff --git a/setup.py b/setup.py
index 6002bb13..63033cb8 100644
--- a/setup.py
+++ b/setup.py
@@ -22,7 +22,7 @@
 
 name = "google-cloud-bigquery-datatransfer"
 description = "BigQuery Data Transfer API client library"
-version = "3.1.0"
+version = "3.1.1"
 # Should be one of:
 # 'Development Status :: 3 - Alpha'
 # 'Development Status :: 4 - Beta'
@@ -30,11 +30,10 @@
 release_status = "Development Status :: 5 - Production/Stable"
 dependencies = (
     "google-api-core[grpc] >= 1.22.2, < 2.0.0dev",
-    "proto-plus >= 1.4.0",
-    "libcst >= 0.2.5",
+    "proto-plus >= 1.15.0",
 )
-extras = {}
 
+extras = {"libcst": "libcst >= 0.2.5"}
 
 # Setup boilerplate below this line.
 
diff --git a/synth.metadata b/synth.metadata
deleted file mode 100644
index aa91c107..00000000
--- a/synth.metadata
+++ /dev/null
@@ -1,145 +0,0 @@
-{
-  "sources": [
-    {
-      "git": {
-        "name": ".",
-        "remote": "https://github.com/googleapis/python-bigquery-datatransfer.git",
-        "sha": "2e73f935dc1a5d96728ab379780271a4b1b02989"
-      }
-    },
-    {
-      "git": {
-        "name": "googleapis",
-        "remote": "https://github.com/googleapis/googleapis.git",
-        "sha": "c13fb8cb376bb666de80ed33e11550955b4357af",
-        "internalRef": "363304304"
-      }
-    },
-    {
-      "git": {
-        "name": "synthtool",
-        "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "79c8dd7ee768292f933012d3a69a5b4676404cda"
-      }
-    },
-    {
-      "git": {
-        "name": "synthtool",
-        "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "79c8dd7ee768292f933012d3a69a5b4676404cda"
-      }
-    }
-  ],
-  "destinations": [
-    {
-      "client": {
-        "source": "googleapis",
-        "apiName": "bigquery_datatransfer",
-        "apiVersion": "v1",
-        "language": "python",
-        "generator": "bazel"
-      }
-    }
-  ],
-  "generatedFiles": [
-    ".coveragerc",
-    ".flake8",
-    ".github/CONTRIBUTING.md",
-    ".github/ISSUE_TEMPLATE/bug_report.md",
-    ".github/ISSUE_TEMPLATE/feature_request.md",
-    ".github/ISSUE_TEMPLATE/support_request.md",
-    ".github/PULL_REQUEST_TEMPLATE.md",
-    ".github/header-checker-lint.yml",
-    ".github/release-please.yml",
-    ".github/snippet-bot.yml",
-    ".gitignore",
-    ".kokoro/build.sh",
-    ".kokoro/continuous/common.cfg",
-    ".kokoro/continuous/continuous.cfg",
-    ".kokoro/docker/docs/Dockerfile",
-    ".kokoro/docker/docs/fetch_gpg_keys.sh",
-    ".kokoro/docs/common.cfg",
-    ".kokoro/docs/docs-presubmit.cfg",
-    ".kokoro/docs/docs.cfg",
-    ".kokoro/populate-secrets.sh",
-    ".kokoro/presubmit/common.cfg",
-    ".kokoro/presubmit/presubmit.cfg",
-    ".kokoro/publish-docs.sh",
-    ".kokoro/release.sh",
-    ".kokoro/release/common.cfg",
-    ".kokoro/release/release.cfg",
-    ".kokoro/samples/lint/common.cfg",
-    ".kokoro/samples/lint/continuous.cfg",
-    ".kokoro/samples/lint/periodic.cfg",
-    ".kokoro/samples/lint/presubmit.cfg",
-    ".kokoro/samples/python3.6/common.cfg",
-    ".kokoro/samples/python3.6/continuous.cfg",
-    ".kokoro/samples/python3.6/periodic-head.cfg",
-    ".kokoro/samples/python3.6/periodic.cfg",
-    ".kokoro/samples/python3.6/presubmit.cfg",
-    ".kokoro/samples/python3.7/common.cfg",
-    ".kokoro/samples/python3.7/continuous.cfg",
-    ".kokoro/samples/python3.7/periodic-head.cfg",
-    ".kokoro/samples/python3.7/periodic.cfg",
-    ".kokoro/samples/python3.7/presubmit.cfg",
-    ".kokoro/samples/python3.8/common.cfg",
-    ".kokoro/samples/python3.8/continuous.cfg",
-    ".kokoro/samples/python3.8/periodic-head.cfg",
-    ".kokoro/samples/python3.8/periodic.cfg",
-    ".kokoro/samples/python3.8/presubmit.cfg",
-    ".kokoro/test-samples-against-head.sh",
-    ".kokoro/test-samples-impl.sh",
-    ".kokoro/test-samples.sh",
-    ".kokoro/trampoline.sh",
-    ".kokoro/trampoline_v2.sh",
-    ".pre-commit-config.yaml",
-    ".trampolinerc",
-    "CODE_OF_CONDUCT.md",
-    "CONTRIBUTING.rst",
-    "LICENSE",
-    "MANIFEST.in",
-    "docs/_static/custom.css",
-    "docs/_templates/layout.html",
-    "docs/bigquery_datatransfer_v1/data_transfer_service.rst",
-    "docs/bigquery_datatransfer_v1/services.rst",
-    "docs/bigquery_datatransfer_v1/types.rst",
-    "docs/conf.py",
-    "docs/multiprocessing.rst",
-    "google/cloud/bigquery_datatransfer/__init__.py",
-    "google/cloud/bigquery_datatransfer/py.typed",
-    "google/cloud/bigquery_datatransfer_v1/__init__.py",
-    "google/cloud/bigquery_datatransfer_v1/proto/datatransfer.proto",
-    "google/cloud/bigquery_datatransfer_v1/proto/transfer.proto",
-    "google/cloud/bigquery_datatransfer_v1/py.typed",
-    "google/cloud/bigquery_datatransfer_v1/services/__init__.py",
-    "google/cloud/bigquery_datatransfer_v1/services/data_transfer_service/__init__.py",
-    "google/cloud/bigquery_datatransfer_v1/services/data_transfer_service/async_client.py",
-    "google/cloud/bigquery_datatransfer_v1/services/data_transfer_service/client.py",
-    "google/cloud/bigquery_datatransfer_v1/services/data_transfer_service/pagers.py",
-    "google/cloud/bigquery_datatransfer_v1/services/data_transfer_service/transports/__init__.py",
-    "google/cloud/bigquery_datatransfer_v1/services/data_transfer_service/transports/base.py",
-    "google/cloud/bigquery_datatransfer_v1/services/data_transfer_service/transports/grpc.py",
-    "google/cloud/bigquery_datatransfer_v1/services/data_transfer_service/transports/grpc_asyncio.py",
-    "google/cloud/bigquery_datatransfer_v1/types/__init__.py",
-    "google/cloud/bigquery_datatransfer_v1/types/datatransfer.py",
-    "google/cloud/bigquery_datatransfer_v1/types/transfer.py",
-    "mypy.ini",
-    "noxfile.py",
-    "renovate.json",
-    "samples/AUTHORING_GUIDE.md",
-    "samples/CONTRIBUTING.md",
-    "samples/snippets/noxfile.py",
-    "scripts/decrypt-secrets.sh",
-    "scripts/fixup_bigquery_datatransfer_v1_keywords.py",
-    "scripts/readme-gen/readme_gen.py",
-    "scripts/readme-gen/templates/README.tmpl.rst",
-    "scripts/readme-gen/templates/auth.tmpl.rst",
-    "scripts/readme-gen/templates/auth_api_key.tmpl.rst",
-    "scripts/readme-gen/templates/install_deps.tmpl.rst",
-    "scripts/readme-gen/templates/install_portaudio.tmpl.rst",
-    "setup.cfg",
-    "testing/.gitignore",
-    "tests/unit/gapic/bigquery_datatransfer_v1/__init__.py",
-    "tests/unit/gapic/bigquery_datatransfer_v1/test_data_transfer_service.py"
-  ]
-}
\ No newline at end of file
diff --git a/testing/constraints-3.6.txt b/testing/constraints-3.6.txt
index d071c726..28be0fe2 100644
--- a/testing/constraints-3.6.txt
+++ b/testing/constraints-3.6.txt
@@ -6,5 +6,5 @@
 # e.g., if setup.py has "foo >= 1.14.0, < 2.0.0dev",
 # Then this file should have foo==1.14.0
 google-api-core==1.22.2
-proto-plus==1.4.0
-libcst==0.2.5
\ No newline at end of file
+proto-plus==1.15.0
+libcst==0.2.5