code: public BoxRequestsBookmark.AddCommentToBookmark getAddCommentRequest(String bookmarkId, String message) {
          BoxRequestsBookmark.AddCommentToBookmark request = new BoxRequestsBookmark.AddCommentToBookmark(bookmarkId, message, getCommentUrl(), mSession);
          return request;
      }
docs: Gets a request that adds a comment to a bookmark
  
  @param bookmarkId    id of the bookmark to add the comment to
  @param message   message for the comment that will be added
  @return  request to add a comment to a bookmark