upgradeInfo method
Implementation
@override
Future<Map<dynamic, dynamic>?> upgradeInfo(
{required String oldSku,
required String skuDetailJson,
int? prorationMode}) async {
return await methodChannel.invokeMethod<Map<dynamic, dynamic>>(
'upgradeInfo', {
'skuDetailJson': skuDetailJson,
'oldSku': oldSku,
'prorationMode': prorationMode
});
}