code: private void sameValueMergeRows(MergeRow mergeRowAnn, int itemSize, Cell fromCell) {
          String lastValue = PoiUtil.getCellStringValue(fromCell);
          int preRow = fromCell.getRowIndex();
          val col = fromCell.getColumnIndex();
          int i = preRow + 1;
  
          for (final int ii = preRow + itemSize; i < ii; ++i) {
              val cell = sheet.getRow(i).getCell(col);
              val cellValue = PoiUtil.getCellStringValue(cell);
              if (StringUtils.equals(cellValue, lastValue)) continue;
  
              directMergeRows(mergeRowAnn, preRow, i - 1, col);
              lastValue = cellValue;
              preRow = i;
          }
  
          directMergeRows(mergeRowAnn, preRow, i - 1, col);
      }
docs: 同值纵向合并单元格。
  
  @param mergeRowAnn 纵向合并单元格注解。
  @param itemSize    纵向合并行数。
  @param fromCell    开始合并单元格。