Specifies how port is selected for health checking, can be one of following values: USE_FIXED_PORT: The port number in port is used for health checking. USE_NAMED_PORT: The portName is used for health checking. USE_SERVING_PORT: For NetworkEndpointGroup, the port specified for each network endpoint is used for health checking. For other backends, the port or named port specified in the Backend Service is used for health checking. If not specified, gRPC health check follows behavior specified in port and portName fields.
A value indicating that the enum field is not set.
UseFixedPort
The port number in port is used for health checking.
UseNamedPort
The portName is used for health checking.
UseServingPort
For NetworkEndpointGroup, the port specified for each network endpoint is used for health checking. For other backends, the port or named port specified in the Backend Service is used for health checking.