Unable to display payment button after configuration completion

Describe the bug
After operating according to usage, the payment button cannot be displayed

Expected behavior
I would like to see a payment button

Screenshots
If applicable, add screenshots to help explain your problem.

flutter doctor output
Include a copy of the output after running flutter doctor if you suspect your issue is related with structural properties in Flutter or other libraries.

Additional context
var googlePayButton = GooglePayButton(
paymentConfiguration: PaymentConfiguration.fromJsonString(defaultGooglePay),
paymentItems: [
PaymentItem(
amount: "0.01",
label: "item A",
status: PaymentItemStatus.final_price
),
PaymentItem(
amount: "0.01",
label: "item B",
status: PaymentItemStatus.final_price
)
],
width: double.infinity,
type: GooglePayButtonType.buy,
margin: const EdgeInsets.only(top: 15),
onPaymentResult: (Map<String, dynamic> result) {
debugPrint("Payment Result: $result");
},
loadingIndicator: const Center(child: CircularProgressIndicator(),),
);
const String defaultGooglePay = '''{
"provider": "google_pay",
"data": {
"environment": "TEST",
"apiVersion": 2,
"apiVersionMinor": 0,
"allowedPaymentMethods": [
{
"type": "CARD",
"tokenizationSpecification": {
"type": "PAYMENT_GATEWAY",
"parameters": {
"gateway": "example",
"gatewayMerchantId": "exampleGatewayMerchantId"
}
},
"parameters": {
"allowedCardNetworks": ["VISA", "MASTERCARD"],
"allowedAuthMethods": ["PAN_ONLY", "CRYPTOGRAM_3DS"],
"billingAddressRequired": true,
"billingAddressParameters": {
"format": "FULL",
"phoneNumberRequired": true
}
}
}
],
"merchantInfo": {
"merchantName": "Example Merchant Name"
},
"transactionInfo": {
"countryCode": "US",
"currencyCode": "USD"
}
}
}''';

Start by reproducing the issue with the shown GooglePayButton configuration and inspect the Flutter plugin's button rendering path. Confirm whether the configuration or runtime environment prevents rendering, and consider the issue done when the payment button displays with the provided setup.