How to Integrate Google Pay With Flutter?

Question

I want to integrate Google Pay With Flutter. I Have Tried and successfully Integrate in Test Mode But not in Production/Release Mode. I Have Followed Some Points First , I used a Pay Package

pay: ^1.0.8

Second I Created a Test gpay.json File

{
    "provider": "google_pay",
    "data": {
        "environment": "Test",
        "apiVersion": 2,
        "apiVersionMinor": 0,
        "allowedPaymentMethods": [{
            "type": "CARD",
            "tokenizationSpecification": {
                "type": "PAYMENT_GATEWAY",
                "parameters": {
                    "gateway": "Exapmle",
                    "gatewayMerchantId": "Example"
                }
            },
            "parameters": {
                "allowedCardNetworks": ["AMEX", "DISCOVER", "INTERAC", "JCB", "MASTERCARD", "MIR", "VISA"],
                "allowedAuthMethods": ["PAN_ONLY", "CRYPTOGRAM_3DS"],
                "billingAddressRequired": true,
                "billingAddressParameters": {
                    "format": "FULL",
                    "phoneNumberRequired": true
                }
            }
        }
        ],
        "merchantInfo": {
            "merchantId": "example",
            "merchantName": "Example"
        },
        "transactionInfo": {
            "countryCode": "US",
            "currencyCode": "USD"
        }
    }
}

Now I want to Integrate Google pay in Production Mode I have created a Google Business Console Account

but I dont know What's the reason behind i can't Integrate If anyone Here to help me out of this It will be thankful