@Override
  public boolean awaitTermination(long duration, TimeUnit unit) throws InterruptedException {
    return backgroundResources.awaitTermination(duration, unit);
  }
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/v1/stub/GrpcExecutionsStub.java