result = mServerListeners.add(listener);
HashSet clone = (HashSet)mServerListeners.clone(); result = clone.add(listener); mServerListeners = clone;
	public boolean addServerListener(ServerListener listener)	{		if (null == listener)	throw new IllegalArgumentException("listener can't be null.");		boolean result = false;				synchronized (mServerListenersMonitor)		{			if (!mServerListeners.contains(listener))			{				result = mServerListeners.add(listener);			}			else			{				result = true;			}		}				assert true == mServerListeners.contains(listener);				return result;	}