code: public void sessionDestroyed(HttpSessionEvent event) {
      if (null != eventMulticaster) {
        eventMulticaster.multicast(new HttpSessionDestroyedEvent(event.getSession()));
      }
    }
docs: Handles the HttpSessionEvent by publishing a {@link HttpSessionDestroyedEvent} to the
  application appContext.
  
  @param event The HttpSessionEvent pass in by the container