docs: public CdnResult.BandwidthResult getBandwidthData(String[] domains, String startDate, String endDate,
                                                        String granularity) throws QiniuException {
          HashMap<String, String> req = new HashMap<>();
          req.put("domains", StringUtils.join(domains, ";"));
          req.put("startDate", startDate);
          req.put("endDate", endDate);
          req.put("granularity", granularity);
  
          byte[] body = Json.encode(req).getBytes(Constants.UTF_8);
          String url = server + "/v2/tune/bandwidth";
          StringMap headers = auth.authorizationV2(url, "POST", body, Client.JsonMime);
          Response response = client.post(url, body, headers, Client.JsonMime);
          return response.jsonToObject(CdnResult.BandwidthResult.class);
      }