发起商家转账API

报错，不知道啥意思

POST https://api.mch.weixin.qq.com/v3/transfer/batches` 
resulted in a `400 Bad Request` 
response: {"code":"PARAM_ERROR","detail":{"location":null,"value":""},"message":"输入源“/appid”映射到字段“商户appi (truncated...)