code: public static MessageSendResult messageMassSendall(String access_token, MassMessage massMessage) {
          String str = JsonUtil.toJSONString(massMessage);
          return messageMassSendall(access_token, str);
      }
docs: 高级群发接口 根据 分组或标签  进行群发
  
  @param access_token access_token
  @param massMessage  massMessage
  @return MessageSendResult