code: public function resolve(Comment $comment, Request $request)
      {
          $em = $this->getDoctrine()->getManager();
          $postId = $request->query->get('post');
          $itemForm = $request->get('comment_front');
  
          if( $this->container->get('security.authorization_checker')->isGranted('IS_AUTHENTICATED_FULLY') ){
              $comment->setActor($this->container->get('security.token_storage')->getToken()->getUser());
          }else{
              //register user
              $actor = $this->createActor($itemForm);
              $comment->setActor($actor);
          }
          
          $postRepository = $em->getRepository('BlogBundle:Post');
          if (!$postId || !$post = $postRepository->find($postId)) {
              // no product id given, or product not found
              throw new \Exception('Requested post was not found');
          }
  
          // assign the product and quantity to the item
          $comment->setPost($post);
          $comment->setComment($itemForm['comment']);
          
          return $comment;
      }
docs: @param Comment $comment
  @param Request $request
  
  @throws ItemResolvingException
  @return CartItemInterface|void