给小程序广告接入在数据回传反回了

接口文档是这个:https://ad.weixin.qq.com/main.html#/docs/233

 
报了这个错误，请问是什么原因:
{"errcode":900351002,"errmsg":"payloads: java.lang.IllegalStateException: Expected BEGIN_ARRAY but was STRING at line 1 column 13 path $.actions"}