get Event Class
Gets the class of the events this listener handled. If it handled multiple classes of event, the closest shared superclass will be returned, such that for any event this listener has handled, this.getEventClass().isAssignableFrom(event.getClass()) and no class this.getEventClass().isAssignableFrom(clazz)
&& this.getEventClass() != clazz &&
event.getClass().isAssignableFrom(clazz) for all handled events.
Return
the event class handled by this RegisteredListener