private PaymentResponseMessage(string registerId, string customerId, decimal paymentAmountProvided, DrinkRequestMessage customerOrder)
 {
     RegisterId = registerId;
     CustomerId = customerId;
     PaymentAmountProvided = paymentAmountProvided;
     CustomerOrder = customerOrder;
 }
 public static PaymentResponseMessage Create(string registerId, string customerId, decimal paymentAmountProvided, DrinkRequestMessage customerOrder)
 {
     return new PaymentResponseMessage(registerId, customerId, paymentAmountProvided, customerOrder);
 }
 public static PaymentRequestMessage Create(string registerId, string recipientId, decimal paymentAmountRequested, DrinkRequestMessage customerResponse)
 {
     return new PaymentRequestMessage(registerId, recipientId, paymentAmountRequested, customerResponse);
 }