unionpay - securepay

{
    "amount": "1.77",
    "currency": "SGD",
    "payment_method": {
        "type": "unionpay",
        "unionpay": {
            "flow": "securepay",
            "is_present": false
        }
    },
    "merchant_order_id": "{{$guid}}",
    "description": "acquiring sandbox testing",
    "metadata": {
        "request_id": "{{$guid}}"
    },
    "return_url": "https://127.0.0.1:8080/api/v1/callback"
}