if (gracefulShutdownFuture == null) { gracefulShutdownFuture = gracefulShutdownCoordinator .startGracefulShutdown(createGracefulShutdownCallable());
if (gracefulShutdownFuture == null) { gracefulShutdownFuture = gracefulShutdownCoordinator .startGracefulShutdown(createGracefulShutdownCallable());