Promotion 支付宝境外收单(create_forex_trade) create_forex_trade out_trade_no: ! Remarks: It is the merchant trade number. No special characters. Subject: ! Remarks：It is the product name. No special characters. Currency: ! Remarks: Settlement currency that merchants signed with Alipay, like USD Total_fee: ! Remarks: The product price in settlement currency Body: ! Remarks:It is the description of the product. Optional.