code: public static void shutdown(@Nonnull final ExecutorService executorService) {
  		Check.notNull(executorService, "executorService");
  		shutdown(executorService, SHUTDOWN_DURATION, TimeUnit.SECONDS);
  	}
docs: Shutdowns the given {@code ExecutorService} as soon as possible, but not later than the specified default time
  (which is {@value #SHUTDOWN_DURATION} seconds).
  
  @param executorService
  executor to stop