s, 
 allowing for more centralized processing than per class defined callback methods.  The external listener 
 receives events when unmarshalling process is marshalling to a Jakarta XML Binding element or to Jakarta XML Binding mapped class.
 <p>
 The 'class defined' and external listener event callback methods are independent of each other,
 both can be called for one event.  The invocation ordering when both listener callback methods exist is
 defined in <a href="Unmarshaller.Listener.html#beforeUnmarsha