code: public static Media mediaUploadnews(String access_token,List<Article> articles){
  		String str = JsonUtil.toJSONString(articles);
  		String messageJson = "{\"articles\":"+str+"}";
  		return mediaUploadnews(access_token, messageJson);
  	}
docs: 高级群发 构成 MassMPnewsMessage 对象的前置请求接口
  @param access_token access_token
  @param articles 图文信息 1-10 个
  @return Media