RefundRequest

{
    "mchId": "MCH20231120001",
    "uniqueOrderNo": "PAY20231120154523001",
    "refundNo": "REFUND20231120000001",
    "refundAmt": 50,
    "description": "用户申请退款",
    "memo": "部分退款",
    "notifyUrl": "https://merchant.example.com/refund-notify"
}