src/net/java/sip/communicator/service/protocol/AbstractOperationSetBasicInstantMessaging.java
/**
     * Registers a MessageListener with this operation set so that it gets
     * notifications of successful message delivery, failure or reception of
     * incoming messages..
     *
     * @param listener the <tt>MessageListener</tt> to register.
     */
Registers a MessageListener with this operation set so that it gets
notifications of successful message delivery, failure or reception of
incoming messages

@param listener the MessageListener to register.
Registers a MessageListener with this operation set so that it gets notifications of successful message delivery failure or reception of incoming messages @param listener the MessageListener to register .
public void addMessageListener(MessageListener listener)
    {
        synchronized (messageListeners)
        {
            if (!messageListeners.contains(listener))
            {
                messageListeners.add(listener);
            }
        }
    }
public void addMessageListener ( MessageListener listener ) { synchronized ( messageListeners ) { if ( ! messageListeners . contains ( listener ) ) { messageListeners . add ( listener ) ; } } }
Registers a MessageListener with this operation set so that it gets
 notifications of successful message delivery, failure or reception of
 incoming messages..
Registers a MessageListener with this operation set so that it gets notifications of successful message delivery failure or reception of incoming messages ..