docs: public UserPagination listUsers(int tagId, String nextOpenId) {
          Map<String, Object> map = new HashMap<>();
          map.put("tagid", tagId);
          String url = WxEndpoint.get("url.tag.user.list");
          if (nextOpenId == null || "".equals(nextOpenId)) {
          } else {
              map.put("next_openid", nextOpenId);
          }
  
          String response = wxClient.post(url, JsonMapper.defaultMapper().toJson(map));
          logger.debug("list tag users: {}", response);
  
          return JsonMapper.defaultMapper().fromJson(response, UserPagination.class);
      }