result = mBotListeners.remove(listener);
HashSet clone = (HashSet)mBotListeners.clone(); result = clone.remove(listener); mBotListeners = clone;
	public boolean removeBotListener(BotListener listener)	{		if (null == listener)	throw new IllegalArgumentException("listener can't be null.");        boolean result = false;				synchronized (mBotListenersMonitor)		{			result = mBotListeners.remove(listener);		}				assert false == mBotListeners.contains(listener);				return result;	}