public static PaymentServiceProxy <T> GetInstance()
 {
     if (instance == null)
     {
         instance = new PaymentServiceProxy <T>();
     }
     return(instance);
 }
 public CashDeskController(ILogger <CashDeskController> logger)
 {
     _logger             = logger;
     paymentServiceProxy = PaymentServiceProxy <IEnumerable <string> > .GetInstance();
 }
 public PaymentMethodsController(ILogger <PaymentMethodsController> logger)
 {
     _logger             = logger;
     paymentServiceProxy = PaymentServiceProxy <IEnumerable <string> > .GetInstance();
 }