api：

https://api.weixin.qq.com/cgi-bin/material/get_material?access_token=45_bjLgYPnmZLrU47k2wzgdQsucxdUwLUnRgYhA6fc5Rkno3wu2tG7SviGkU8Gqy6pNYW0auWuc9zRaNYyTZLD1QcFMsyPjxGJDaLuM4JpYYmCr2imSugskWSvJbITTJTGb9J-4A7TzXQEtFaywGLAcAGDZET

参数：&mediaId=J-VQL7ca2JlPL4nusH9Ya-3u6gb8FAW4-RW4Hdee46s

响应内容：

{

	"title": "金牌分析师：券商股左侧配置时机或已到丨大咖录",

	"author": "第一财经",

	"digest": "点击阅读",

	"content": "xxx

	"content\_source\_url": "",

	"thumb\_media\_id": "",

	"show\_cover\_pic": 0,

	"url": "xxx ,

	"thumb\_url": "xxx ",

	"need\_open\_comment": 0,

	"only\_fans\_can\_comment": 0

}

这个图文title下的 thumb_media_id 为什么是空的；