Get the most expensive product by category

MostExpensiveProduct.java

    @RequestMapping("/most-expensive")
    Map<String, Optional<Product>> getMostExpensiveProductByCategory () {
        Map<String, Optional<com.mycompany.functional.programming.exercises.models.Product>> mostExpensiveByCategory = productRepos.findAll().stream().collect(Collectors.groupingBy(
                    com.mycompany.functional.programming.exercises.models.Product::getCategory,
                    Collectors.maxBy(Comparator.comparing(com.mycompany.functional.programming.exercises.models.
                            Product::getPrice)
                 )
         ));
        Map<String, Optional<Product>> ordersByCustomerTransformed = new HashMap();
        mostExpensiveByCategory.entrySet().stream().forEach(e -> {
            ordersByCustomerTransformed.put(e.getKey(), Optional.of(new Product(e.getValue().get().getId(),
                    e.getValue().get().getName(), e.getValue().get().getPrice(), e.getValue().get().getCategory())));
        });
        return ordersByCustomerTransformed;
    }