docs: public static <T, X> ObserverMethodImpl<T, X> create(EnhancedAnnotatedMethod<T, ? super X> method, RIBean<X> declaringBean, BeanManagerImpl manager, boolean isAsync) {
          if (declaringBean instanceof ExtensionBean) {
                  return new ExtensionObserverMethodImpl<T, X>(method, declaringBean, manager, isAsync);
          }
          return new ObserverMethodImpl<T, X>(method, declaringBean, manager, isAsync);
      }