proceedGooglePayPayment method 
    
      
Future<void>
proceedGooglePayPayment(
 - Map<String, dynamic> request, 
- Map<String, dynamic>? fx, 
- int googlePayAPIEnvironment, 
- dynamic response( - Map<String, dynamic>
 ),
- dynamic error( - dynamic
 ),
) 
    
    
  Implementation
  Future<void> proceedGooglePayPayment(Map<String, dynamic> request, Map<String, dynamic>? fx, int googlePayAPIEnvironment, Function(Map<String, dynamic>) response, Function(dynamic) error) async {
  try {
    response.call(json.decode(
      await _apiHelper.proceedGooglePayPayment(
        json.encode(request),
        fx != null ? json.encode(fx) : null,
        googlePayAPIEnvironment
      )
    ));
  } catch (e) {
    error.call(e);
  }
}