code: function _updateRowspan(tableData, startRowIndex, endRowIndex) {
    util.range(startRowIndex, endRowIndex + 1).forEach(rowIndex => {
      tableData[rowIndex].forEach((cell, cellIndex) => {
        if (util.isExisty(cell.rowMergeWith)) {
          const merger = tableData[cell.rowMergeWith][cellIndex];
  
          if (merger.rowspan) {
            merger.rowspan -= 1;
          }
        } else if (cell.rowspan > 1) {
          const lastMergedRowIndex = rowIndex + cell.rowspan - 1;
  
          cell.rowspan -= (endRowIndex - rowIndex + 1);
  
          if (lastMergedRowIndex > endRowIndex) {
            tableData[endRowIndex + 1][cellIndex] = util.extend({}, cell);
          }
        }
      });
    });
  }
docs: Update rowspan to row merger.
  @param {Array.<Array.<object>>} tableData - table data
  @param {number} startRowIndex - start row index
  @param {number} endRowIndex - end row index
  @private