code: public static void installAsShutdownHook(Logger logger, long delayMillis) {
  		checkArgument(delayMillis >= 0, "delay must be >= 0");
  
  		// install the blocking shutdown hook
  		Thread shutdownHook = new JvmShutdownSafeguard(delayMillis);
  		ShutdownHookUtil.addShutdownHookThread(shutdownHook, JvmShutdownSafeguard.class.getSimpleName(), logger);
  	}
docs: Installs the safeguard shutdown hook. The maximum time that the JVM is allowed to spend
  on shutdown before being killed is the given number of milliseconds.
  
  @param logger      The logger to log errors to.
  @param delayMillis The delay (in milliseconds) to wait after clean shutdown was stared,
  before forcibly terminating the JVM.