private static void createCase11(String filename) throws IOException {
HSSFWorkbook wb = new HSSFWorkbook();
HSSFSheet sheet1 = wb.createSheet("new sheet");
sheet1.groupRow(5, 14);
sheet1.groupRow(7, 10);
sheet1.setRowGroupCollapsed(7, true);
sheet1.setRowGroupCollapsed(5, true);
sheet1.setRowGroupCollapsed(8, false);
sheet1.setRowGroupCollapsed(14, false);