@Override
 public Comment addComment(Comment comment) throws ResourceNotFoundException {
   Long createdId = commentsDao.save(comment);
   if (createdId == null) {
     throw new ResourceNotFoundException(String.format("[Article id=%s", comment.getArticleId()));
   }
   comment.setId(createdId);
   return comment;
 }
 @Override
 public List<Comment> getComments(long articleId) {
   return commentsDao.getComments(articleId);
 }