public List <ProductDTO> GetProductsByIdList(List <int> productIdList)
        {
            var allProductsList = _productRepository.LoadProducts(productIdList);
            var productDTOList  = ProductDTOBuilder.MapProductsToDTOList(allProductsList);

            return(productDTOList);
        }
        public ProductDTO GetProductById(int productId)
        {
            var product    = _productRepository.LoadProductById(productId);
            var productDTO = ProductDTOBuilder.MapProductToDTO(product);

            return(productDTO);
        }