code: public boolean isSet(_Fields field) {
      if (field == null) {
        throw new IllegalArgumentException();
      }
  
      switch (field) {
      case OPERATION_ID:
        return isSetOperationId();
      case OPERATION_TYPE:
        return isSetOperationType();
      case HAS_RESULT_SET:
        return isSetHasResultSet();
      case MODIFIED_ROW_COUNT:
        return isSetModifiedRowCount();
      }
      throw new IllegalStateException();
    }
docs: Returns true if field corresponding to fieldID is set (has been assigned a value) and false otherwise