code: public static void removeOtherSheets(Sheet sheet) {
          val wb = sheet.getWorkbook();
  
          List<String> deletedNames = Lists.newArrayList();
          for (int i = 0; i < wb.getNumberOfSheets(); ++i) {
              val sheetName = wb.getSheetName(i);
              if (!sheetName.equals(sheet.getSheetName())) {
                  deletedNames.add(sheetName);
              }
          }
  
          deletedNames.forEach(x -> wb.removeSheetAt(wb.getSheetIndex(x)));
      }
docs: 删除其它Sheet页，只保留指定模板的Sheet页输出。
  
  @param sheet 在工作簿需要保留的表单页。