docs: @RequestMapping(value = "/downloadfilebatch", method = RequestMethod.GET)
      public HttpEntity<byte[]> download2(@Valid ConfListForm confListForm) {
  
          LOG.info(confListForm.toString());
  
          //
          // get files
          //
          List<File> fileList = configMgr.getDisconfFileList(confListForm);
  
          //
          // prefix
          //
          String prefixString =
                  "APP" + confListForm.getAppId() + "_" + "ENV" + confListForm.getEnvId() + "_" + "VERSION" +
                          confListForm.getVersion();
  
          HttpHeaders header = new HttpHeaders();
  
          String targetFileString = "";
          File targetFile = null;
          byte[] res = null;
          try {
              targetFileString = TarUtils.tarFiles("tmp", prefixString, fileList);
              targetFile = new File(targetFileString);
              res = IOUtils.toByteArray(new FileInputStream(targetFile));
          } catch (Exception e) {
              throw new DocumentNotFoundException("");
          }
  
          header.set("Content-Disposition", "attachment; filename=" + targetFile.getName());
          header.setContentLength(res.length);
          return new HttpEntity<byte[]>(res, header);
      }