code: public void notifySipApplicationSessionListeners(SipApplicationSessionEventType sipApplicationSessionEventType) {
  		List<SipApplicationSessionListener> listeners =
  			sipContext.getListeners().getSipApplicationSessionListeners();
  		if(listeners.size() > 0) {
  			ClassLoader oldClassLoader = java.lang.Thread.currentThread().getContextClassLoader();
  			sipContext.enterSipContext();
  			SipApplicationSessionEvent event = new SipApplicationSessionEvent(this.getFacade());
  			if(logger.isDebugEnabled()) {
  				logger.debug("notifying sip application session listeners of context " +
  						key.getApplicationName() + " of following event " + sipApplicationSessionEventType);
  			}
  			for (SipApplicationSessionListener sipApplicationSessionListener : listeners) {
  				try {
  					if(logger.isDebugEnabled()) {
  						logger.debug("notifying sip application session listener " + sipApplicationSessionListener.getClass().getName() + " of context " +
  								key.getApplicationName() + " of following event " + sipApplicationSessionEventType);
  					}
  					if(SipApplicationSessionEventType.CREATION.equals(sipApplicationSessionEventType)) {
  						sipApplicationSessionListener.sessionCreated(event);
  					} else if (SipApplicationSessionEventType.DELETION.equals(sipApplicationSessionEventType)) {
  						sipApplicationSessionListener.sessionDestroyed(event);
  					} else if (SipApplicationSessionEventType.EXPIRATION.equals(sipApplicationSessionEventType)) {
  						sipApplicationSessionListener.sessionExpired(event);
  					} else if (SipApplicationSessionEventType.READYTOINVALIDATE.equals(sipApplicationSessionEventType)) {
  						sipApplicationSessionListener.sessionReadyToInvalidate(event);
  					}
  
  				} catch (Throwable t) {
  					logger.error("SipApplicationSessionListener threw exception", t);
  				}
  			}
  			sipContext.exitSipContext(oldClassLoader);
  		}
  	}
docs: Notifies the listeners that a lifecycle event occured on that sip application session
  @param sipApplicationSessionEventType the type of event that happened