code: public synchronized void addListener(String threadPrefix,
  			EventListener listener) {
  		if (threadPrefix.trim().equals("")) {
  			globalListeners.addElement(listener);
  		} else {
  			keyedListeners.put(threadPrefix.trim(), listener);
  		}
  	}
docs: Add a J2SSH Listener to the list of listeners that will be sent events
  
  @param threadPrefix
  listen to threads whose name have this prefix, string must not
  contain any '-' except the final character which must be a
  '-'.
  @param listener