fix: fix mTLS logic

gapic/templates/%namespace/%name_%version/%sub/services/%service/client.py.j2

@@ -91,7 +91,6 @@ class {{ service.client_name }}(metaclass={{ service.client_name }}Meta):
  DEFAULT_MTLS_ENDPOINT = _get_default_mtls_endpoint.__func__( # type: ignore
  DEFAULT_ENDPOINT
  )
- DEFAULT_OPTIONS = ClientOptions.ClientOptions(api_endpoint=DEFAULT_ENDPOINT)
 
  @classmethod
  def from_service_account_file(cls, filename: str, *args, **kwargs):
@@ -126,7 +125,7 @@ class {{ service.client_name }}(metaclass={{ service.client_name }}Meta):
  def __init__(self, *,
  credentials: credentials.Credentials = None,
  transport: Union[str, {{ service.name }}Transport] = None,
- client_options: ClientOptions = DEFAULT_OPTIONS,
+ client_options: ClientOptions = None,
  ) -> None:
  """Instantiate the {{ (service.client_name|snake_case).replace('_', ' ') }}.
 
@@ -144,11 +143,10 @@ class {{ service.client_name }}(metaclass={{ service.client_name }}Meta):
  default endpoint provided by the client.
  (2) If ``transport`` argument is None, ``client_options`` can be
  used to create a mutual TLS transport. If ``api_endpoint`` is
- provided and different from the default endpoint, or the
- ``client_cert_source`` property is provided, mutual TLS
- transport will be created if client SSL credentials are found.
- Client SSL credentials are obtained from ``client_cert_source``
- or application default SSL credentials.
+ provided or the ``client_cert_source`` property is provided,
+ mutual TLS transport will be created if client SSL credentials
+ are found. Client SSL credentials are obtained from
+ ``client_cert_source`` or application default SSL credentials.
 
  Raises:
  google.auth.exceptions.MutualTlsChannelError: If mutual TLS transport
@@ -157,10 +155,6 @@ class {{ service.client_name }}(metaclass={{ service.client_name }}Meta):
  if isinstance(client_options, dict):
  client_options = ClientOptions.from_dict(client_options)
 
- # Set default api endpoint if not set.
- if client_options.api_endpoint is None:
- client_options.api_endpoint = self.DEFAULT_ENDPOINT
-
  # Save or instantiate the transport.
  # Ordinarily, we provide the transport, but allowing a custom transport
  # instance provides an extensibility point for unusual situations.
@@ -170,24 +164,27 @@ class {{ service.client_name }}(metaclass={{ service.client_name }}Meta):
  raise ValueError('When providing a transport instance, '
  'provide its credentials directly.')
  self._transport = transport
- elif transport is not None or (
- client_options.api_endpoint == self.DEFAULT_ENDPOINT
+ elif client_options is None or (
+ client_options.api_endpoint == None
  and client_options.client_cert_source is None
  ):
- # Don't trigger mTLS.
+ # Don't trigger mTLS if we get an empty ClientOptions.
  Transport = type(self).get_transport_class(transport)
  self._transport = Transport(
- credentials=credentials, host=client_options.api_endpoint
+ credentials=credentials, host=self.DEFAULT_ENDPOINT
  )
  else:
- # Trigger mTLS. If the user overrides endpoint, use it as the mTLS
- # endpoint, otherwise use the default mTLS endpoint.
- option_endpoint = client_options.api_endpoint
- api_mtls_endpoint = self.DEFAULT_MTLS_ENDPOINT if option_endpoint == self.DEFAULT_ENDPOINT else option_endpoint
+ # We have a non-empty ClientOptions, trigger mTLS. If the user
+ # doesn't provide endpoint, use the default mTLS endpoint.
+ if client_options.api_endpoint:
+ api_endpoint = api_mtls_endpoint = client_options.api_endpoint
+ else:
+ api_endpoint = self.DEFAULT_ENDPOINT
+ api_mtls_endpoint = self.DEFAULT_MTLS_ENDPOINT
 
  self._transport = {{ service.name }}GrpcTransport(
  credentials=credentials,
- host=client_options.api_endpoint,
+ host=api_endpoint,
  api_mtls_endpoint=api_mtls_endpoint,
  client_cert_source=client_options.client_cert_source,
  )

gapic/templates/tests/unit/%name_%version/%sub/test_%service.py.j2

@@ -64,10 +64,6 @@ def test_{{ service.client_name|snake_case }}_from_service_account_file():
 
 
 def test_{{ service.client_name|snake_case }}_client_options():
- # Check the default options have their expected values.
- assert {{ service.client_name }}.DEFAULT_OPTIONS.api_endpoint == {% if service.host %}'{{ service.host }}'{% else %}None{% endif %}
- assert {{ service.client_name }}.DEFAULT_OPTIONS.api_endpoint == {{ service.client_name }}.DEFAULT_ENDPOINT
-
  # Check that if channel is provided we won't create a new one.
  with mock.patch('{{ (api.naming.module_namespace + (api.naming.versioned_module_name,) + service.meta.address.subpackage)|join(".") }}.services.{{ service.name|snake_case }}.{{ service.client_name }}.get_transport_class') as gtc:
  transport = transports.{{ service.name }}GrpcTransport(