private static void OnGetCartsExecuted(GetCartsDataRequest request, EntityDataServiceResponse <SalesTransaction> response)
            {
                // In order to know customer id associated with the cart it needs to be loaded first, therefore permission check happens after execute.
                var checkAccessRequest = new CheckAccessToCartServiceRequest(response.PagedEntityCollection.Results);

                request.RequestContext.Execute <NullResponse>(checkAccessRequest);
            }
            private static void OnSaveCartExecuting(SaveCartDataRequest request)
            {
                var checkAccessRequest = new CheckAccessToCartServiceRequest(request.SalesTransactions);

                request.RequestContext.Execute <Response>(checkAccessRequest);
            }