@Override
  public void shutdown() {
    backgroundResources.shutdown();
  }
Constructs an instance of GrpcExecutionsStub, 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-workflow-executions/google-cloud-workflow-executions/src/main/java/com/google/cloud/workflows/executions/v1beta/stub/GrpcExecutionsStub.java