code: function _updateMergeStartIndex(tableData, startColIndex, endColIndex) {
    tableData.forEach(rowData => {
      rowData.slice(endColIndex + 1).forEach(cellData => {
        if (util.isExisty(cellData.colMergeWith) && cellData.colMergeWith >= startColIndex) {
          cellData.colMergeWith = endColIndex + 1;
        }
      });
    });
  }
docs: Update row merge start index to merged cell.
  @param {Array.<Array.<object>>} tableData - table data
  @param {number} startColIndex - start col index
  @param {number} endColIndex - end col index
  @private