docs: public Video getVideo(String mediaId) {
          String response = wxClient.get(String.format(WxEndpoint.get("url.material.binary.get"), mediaId));
          Map<String, Object> result = JsonMapper.defaultMapper().json2Map(response);
          if (result.containsKey("title")) {
              return JsonMapper.defaultMapper().fromJson(response, Video.class);
          } else {
              logger.warn("download video failed: {}", response);
              throw new WxRuntimeException(999, response);
          }
      }