code: public static Workbook newWorkbook(InputStream original) {
          try {
              Workbook book = new XSSFWorkbook(original);
              book.addToolPack(Functions.getUdfFinder());
              return book;
          }
          catch (IOException e) { throw new CalculationEngineException(e); }
      }
docs: Creates an instance of new {@link XSSFWorkbook} from {@link InputStream}.