Mesclar celulas no excel (POI)

Workbook wb = new HSSFWorkbook();
    Sheet sheet = wb.createSheet("new sheet");

    Row row = sheet.createRow((short) 1);
    Cell cell = row.createCell((short) 1);
    cell.setCellValue("This is a test of merging");

    sheet.addMergedRegion(new CellRangeAddress(
            1, //first row (0-based)
            1, //last row  (0-based)
            1, //first column (0-based)
            2  //last column  (0-based)
    ));

    // Write the output to a file
    FileOutputStream fileOut = new FileOutputStream("workbook.xls");
    wb.write(fileOut);
    fileOut.close();