@Override
  public void shutdownNow() {
    backgroundResources.shutdownNow();
  }
Constructs an instance of GrpcTraceServiceStub, 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-trace/google-cloud-trace/src/main/java/com/google/cloud/trace/v1/stub/GrpcTraceServiceStub.java