/** Delegate persistence to subclasses then clean up resources. */
 public void dispose() {
   EventRegistryDataWrapper ecdw = wrapRegistry();
   persist(ecdw);
   m_keyMMap.clear();
   m_keyMMap = null;
   m_eventMMap.clear();
   m_eventMMap = null;
 }
 /** Remove all registered data. */
 public void clear() {
   synchronized (this) {
     m_keyMMap.clear();
     m_eventMMap.clear();
   }
 }