docs: public static int mergingCells(Sheet sheet, int firstRow, int lastRow, int firstColumn, int lastColumn, CellStyle cellStyle) {
  		final CellRangeAddress cellRangeAddress = new CellRangeAddress(//
  				firstRow, // first row (0-based)
  				lastRow, // last row (0-based)
  				firstColumn, // first column (0-based)
  				lastColumn // last column (0-based)
  		);
  
  		if (null != cellStyle) {
  			RegionUtil.setBorderTop(cellStyle.getBorderTopEnum(), cellRangeAddress, sheet);
  			RegionUtil.setBorderRight(cellStyle.getBorderRightEnum(), cellRangeAddress, sheet);
  			RegionUtil.setBorderBottom(cellStyle.getBorderBottomEnum(), cellRangeAddress, sheet);
  			RegionUtil.setBorderLeft(cellStyle.getBorderLeftEnum(), cellRangeAddress, sheet);
  		}
  		return sheet.addMergedRegion(cellRangeAddress);
  	}