private void persistExcelTable(ITable t) {
    FileOutputStream out;
    String fileName;

    try (XSSFWorkbook workbook = new XSSFWorkbook()) {
      if (StringUtility.isNullOrEmpty(invokerName)) {
        fileName = "/home/admin/Desktop/YGApp Export "
            + LocalDateTime.now().format(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss"))
            + ".xlsx";
      } else {
        fileName = "/home/admin/Desktop/YGApp " + invokerName + " "
            + LocalDateTime.now().format(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss"))
            + ".xlsx";
      }
      out = new FileOutputStream(new File(fileName));

      XSSFSheet sheet = workbook
          .createSheet(TEXTS.get("Sheet") + String.valueOf(workbook.getNumberOfSheets() + 1));

      ..... more code ....

      //
      workbook.write(out);
       // download the file to the client session
      // See
      // https://www.eclipse.org/forums/index.php/m/1440415/?srch=download+excel+file#msg_1440415
      ClientSession.get().getDesktop().openUri(fileName, OpenUriAction.DOWNLOAD);
    } catch (Exception e) {
      throw new VetoException(e.getMessage());
    }
  }

 ClientSession.get().getDesktop().openUri(fileName, OpenUriAction.DOWNLOAD);

//Create byte[] from excel documents.
public byte[] saveExcelDocument(XSSFWorkbook document) {
		ByteArrayOutputStream out = new ByteArrayOutputStream();
		try {
			document.write(out);
			out.close();
			document.close();

			return out.toByteArray();
		} catch (IOException e) {
			e.printStackTrace();
		}

		return null;
	}

//create BinaryResource object:
byte[] content = saveExcelDocument(excelDocument);
binaryResource = new BinaryResource("myexcelfilename.xlsx", content);

ClientSession.get().getDesktop().openUri(binaryResource, OpenUriAction.DOWNLOAD);