https://developers.weixin.qq.com/miniprogram/dev/platform-capabilities/business-capabilities/ministore/minishopopencomponent2/API/aftersale/add.html

商业能力 /交易组件 /自定义版交易组件及开放接口 /服务端接口 /售后接口 /创建售后

入参有两个退款金额的参数，是什么意思