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/setup.py b/setup.py
index 6002bb13..71b58e70 100644
--- a/setup.py
+++ b/setup.py
@@ -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/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