code: public String addComment(String photosetId, String commentText) throws FlickrException {
          Map<String, Object> parameters = new HashMap<String, Object>();
          parameters.put("method", METHOD_ADD_COMMENT);
  
          parameters.put("photoset_id", photosetId);
          parameters.put("comment_text", commentText);
  
          // Note: This method requires an HTTP POST request.
          Response response = transportAPI.post(transportAPI.getPath(), parameters, apiKey, sharedSecret);
          if (response.isError()) {
              throw new FlickrException(response.getErrorCode(), response.getErrorMessage());
          }
          // response:
          // <comment id="97777-12492-72057594037942601" />
          Element commentElement = response.getPayload();
          return commentElement.getAttribute("id");
      }
docs: Add a comment to a photoset. This method requires authentication with 'write' permission.
  
  @param photosetId
  The id of the photoset to add a comment to.
  @param commentText
  Text of the comment
  @return the comment id
  @throws FlickrException