code: public void addListener( IDmListener listener ) {
  
  		if( listener == null ) {
  			this.logger.info( "An invalid DM listener failed to be added." );
  
  		} else {
  			synchronized( this.dmListeners ) {
  				this.dmListeners.add( listener );
  			}
  
  			if( this.enableNotifications.get())
  				listener.enableNotifications();
  
  			this.logger.info( "The listener '" + listener.getId() + "' is now available in Roboconf's DM." );
  		}
  
  		listListeners();
  	}
docs: Adds a listener.
  @param listener