Produce a data map with order records grouped by customer

GroupByCustomer.java

    @RequestMapping("/group-by-customer")
    public Map<Customer, List<Order>> getOrdersByCustomer () {
        Map<com.mycompany.functional.programming.exercises.models.Customer,
                List<com.mycompany.functional.programming.exercises.models.Order>> ordersByCustomer = orderRepo.
                findAll().stream().collect(Collectors.groupingBy(com.mycompany.functional.programming.exercises.models.
                        Order::getCustomer));
        Map<Customer, List<Order>> ordersByCustomerTransformed = new HashMap();
        ordersByCustomer.forEach((k,v) -> {
            Customer customer = new Customer(k.getId(), k.getName(), k.getTier());
            List<Order> orders = v.stream().map(o -> new Order(o.getId(), o.getOrderDate(), o.getDeliveryDate(), o.getStatus())).
                    collect(Collectors.toList());
            ordersByCustomerTransformed.put(customer, orders);
        });
        return ordersByCustomerTransformed;
    }