code: private void pingNotifiableEventListenerInternal(Object object, String topic, Registration registration, boolean register) {
          if (!(object instanceof NotifiableEventListener)) {
              return;
          }
  
          NotifiableEventListener listener = ((NotifiableEventListener) object);
          if (register) {
              listener.onRegister(service, serviceName, topic, registration);
          } else {
              listener.onDeregister(service, serviceName, topic, registration);
          }
      }
docs: Notifies the object of an event in the lifecycle of the listener. The listener may have
  been registered or deregistered. The object must implement {@link NotifiableEventListener} if
  it wants to be notified.
  
  @param object       the object to notified. It must implement {@link NotifiableEventListener} to be notified
  @param topic        the event topic name
  @param registration the listener registration
  @param register     whether the listener was registered or not