code: public Discussion createDiscussion(long sheetId, long rowId, Discussion discussion) throws SmartsheetException{
          return this.createResource("sheets/" + sheetId + "/rows/" + rowId + "/discussions", Discussion.class, discussion);
      }
docs: Create discussion on a row.
  
  It mirrors to the following Smartsheet REST API method: /sheets/{sheetId}/rows/{rowId}/discussions
  
  Exceptions:
  IllegalArgumentException : if any argument is null
  InvalidRequestException : if there is any problem with the REST API request
  AuthorizationException : if there is any problem with the REST API authorization(access token)
  ServiceUnavailableException : if the REST API service is not available (possibly due to rate limiting)
  SmartsheetRestException : if there is any other REST API related error occurred during the operation
  SmartsheetException : if there is any other error occurred during the operation
  
  @param sheetId the sheet ID
  @param rowId the row ID
  @param discussion the comment to add, limited to the following required attributes: text
  @return the created comment
  @throws SmartsheetException the smartsheet exception