protected List<MessageListener<? super S>> getListeners( Class c, boolean create )
    {
        List<MessageListener<? super S>> result = typeListeners.get(c);
        if( result == null && create ) {
            result = new CopyOnWriteArrayList<MessageListener<? super S>>();
            typeListeners.put( c, result );
        }
        
        if( result == null ) {
            result = Collections.emptyList();
        }
        return result;   
    }
Keeps track of message listeners registered to specific
 types or to any type.

 @version   $Revision$
 @author    Paul Speed
jme3-networking/src/main/java/com/jme3/network/base/MessageListenerRegistry.java