code: private void processInternalListener(Class<?> listenerClass) {
      InternalListenerMetadata listenerMetadata = InternalListenerIntrospector
          .introspect(listenerClass);
      Map<CallbackType, Method> callbacks = listenerMetadata.getCallbacks();
      if (callbacks != null) {
        for (Map.Entry<CallbackType, Method> entry : callbacks.entrySet()) {
          CallbackType callbackType = entry.getKey();
          Method callbackMethod = entry.getValue();
          CallbackMetadata callbackMetadata = new CallbackMetadata(EntityListenerType.INTERNAL,
              callbackType, callbackMethod);
          metadata.put(callbackType, callbackMetadata);
        }
      }
    }
docs: Processes the given class and finds any internal callbacks.
  
  @param listenerClass
  the class to introspect