如何解决云开发调用支付接口出现 errCode:-504002 ？

VM817 WAService.js:2 Error: cloud.callFunction:fail Error: errCode: -504002 functions execute fail | errMsg: Error: 输入源“/body/xml/out_trade_no”映射到字段“商户订单号”必填性规则校验失败，此字段为必填项

Error: cloud.callFunction:fail Error: errCode: -504002 functions execute fail | errMsg: Error: 输入源“/body/xml/out_trade_no”映射到字段“商户订单号”必填性规则校验失败，此字段为必填项
    at Payment._parse (:30423/var/user/node_modules/tenpay/lib/index.js:89)
    at processTicksAndRejections (:30423/appservice/internal/process/task_queues.js:97) (callId: 1633084366826-0.8489910275016763) (trace: 18:32:46 start->18:32:47 system error (Error: errCode: -504002 functions execute fail | errMsg: Error: 输入源“/body/xml/out_trade_no”映射到字段“商户订单号”必填性规则校验失败，此字段为必填项
    at Payment._parse (:30423/var/user/node_modules/tenpay/lib/index.js:89)
    at processTicksAndRejections (:30423/appservice/internal/process/task_queues.js:97)), abort)
    at ar (VM817 WAService.js:2)
    at VM817 WAService.js:2
    at VM817 WAService.js:2
    at n (VM817 WAService.js:2)(env: Windows,mp,1.05.2109101; lib: 2.19.5)