docs: @RequestMapping(value = "/download/{configId}", method = RequestMethod.GET)
      public HttpEntity<byte[]> downloadDspBill(@PathVariable long configId) {
  
          // 业务校验
          configValidator.valideConfigExist(configId);
  
          ConfListVo config = configMgr.getConfVo(configId);
  
          HttpHeaders header = new HttpHeaders();
          byte[] res = config.getValue().getBytes();
          if (res == null) {
              throw new DocumentNotFoundException(config.getKey());
          }
  
          String name = null;
  
          try {
              name = URLEncoder.encode(config.getKey(), "UTF-8");
          } catch (UnsupportedEncodingException e) {
              e.printStackTrace();
          }
  
          header.set("Content-Disposition", "attachment; filename=" + name);
          header.setContentLength(res.length);
          return new HttpEntity<byte[]>(res, header);
      }