code: @Override public int compare(Row leftRow, Row rightRow)
     {
        int result = 0;
        int index = 0;
        while (index < m_sortColumns.length)
        {
           Integer leftValue = leftRow.getInteger(m_sortColumns[index]);
           Integer rightValue = rightRow.getInteger(m_sortColumns[index]);
           result = NumberHelper.compare(leftValue, rightValue);
           if (result != 0)
           {
              break;
           }
           ++index;
        }
  
        return result;
     }
docs: {@inheritDoc}