public CartRetriever(CheckoutEntities checkoutEntities,
                      ICartIdRetriever cartIdRetriever)
 {
     this.checkoutEntities = checkoutEntities;
     this.cartIdRetriever  = cartIdRetriever;
 }
 public CartMigrator(ICartIdRetriever cartIdRetriever,
                     CheckoutEntities checkoutEntities)
 {
     this.cartIdRetriever  = cartIdRetriever;
     this.checkoutEntities = checkoutEntities;
 }