Classes that implement this interface agree to maintain a list of SystemEventListener instances for each kind of SystemEvent they can generate. This interface enables arbitrary Objects to act as the source for SystemEvent instances.

If the implementing class is a UIComponent or is referenced by a UIComponent, care must be taken to ensure that the implementing class, and all the members of the list returned by getListenersForEventClass(java.lang.Class<? extends javax.faces.event.SystemEvent>) work correctly with the state management system. One way to ensure this is to have the class and the list members implement StateHolder or Serializable.