@Override
    public void handleEvent(Object event) throws GuacamoleException {
        for (final Listener listener : listeners) {
            listener.handleEvent(event);
        }
    }
Notifies registered listeners than an event has occurred. Notification continues
until a given listener throws a GuacamoleException or other runtime exception, or
until all listeners have been notified.

@param event
     An object that describes the event that has occurred.

@throws GuacamoleException
     If a registered listener throws a GuacamoleException.
guacamole/src/main/java/org/apache/guacamole/rest/event/ListenerService.java