@Override
	public boolean isShutdown() {
		_lock.lock();
		try {
			return _shutdown;
		} finally {
			_lock.unlock();
		}
	}
Returns {@code true} if this task completion has been shut down.

@return {@code true} if this task completion has been shut down
jenetics.incubator/src/main/java/io/jenetics/incubator/util/TaskCompletion.java