public List<Reference> getLikes(String objectId) {
   return graphApi.fetchConnections(objectId, "likes", Reference.class);
 }
 public void deleteComment(String objectId) {
   requireAuthorization();
   graphApi.delete(objectId);
 }
 public Comment getComment(String commentId) {
   return graphApi.fetchObject(commentId, Comment.class);
 }
 public String addComment(String objectId, String message) {
   requireAuthorization();
   MultiValueMap<String, Object> map = new LinkedMultiValueMap<String, Object>();
   map.set("message", message);
   return graphApi.publish(objectId, "comments", map);
 }
 public List<Comment> getComments(String objectId, int offset, int limit) {
   MultiValueMap<String, String> parameters = new LinkedMultiValueMap<String, String>();
   parameters.set("offset", String.valueOf(offset));
   parameters.set("limit", String.valueOf(limit));
   return graphApi.fetchConnections(objectId, "comments", Comment.class, parameters);
 }