@Override
  public void shutdownNow() {
    backgroundResources.shutdownNow();
  }
Constructs an instance of GrpcEndpointServiceStub, using the given settings. This is protected
so that it is easy to make a subclass, but otherwise, the static factory methods should be
preferred.
java-vertexai/google-cloud-vertexai/src/main/java/com/google/cloud/vertexai/api/stub/GrpcEndpointServiceStub.java