jx:areaColumnMerge(rows="" lastCell="C2")
rows: Number of rows combined
lastCell: must be in same row and marks last column
When many adjacent columns need to be combined vertically in a jx:each row, jx:areaColumnMerge simplifies the writing process compared to jx:mergeCells. See example template cell G3:

Result from testcase AreaColumnMergeTest:

This command can only be used on cells that have not been merged. An exception will occur if the scope of the merged cell exists for the merged cell.
jx:areaColumnMerge is part of jxls-poi and is only available if you use JxlsPoiTemplateFillerBuilder or add the MergeCellsCommand using withCommand().
This command is a community contribution.