code: public <T extends EventListener> T createAsyncListener(Class<T> classToCreate) throws ServletException {
          return super.createListener(classToCreate); 
      }
docs: This method should only be used to create an AsyncListener as the WebApp31.createListener no longer accepts AsyncListeners
  as per the specification.  This method is currently called from AsyncContext31Impl.createListener.
  
  @param classToCreate
  @return
  @throws ServletException