BAEL-2275: Change orderitem to be built based on product

ddd/src/test/java/com/baeldung/ddd/layers/domain/OrderUnitTest.java

@@ -50,12 +50,12 @@ class OrderUnitTest {
     @Test
     void shouldRemoveProduct_thenUpdatePrice() {
         final Order order = OrderProvider.getCreatedOrder();
-
-        order.removeOrder(order
+        final UUID productId = order
           .getOrderItems()
           .get(0)
-          .getProduct()
-          .getId());
+          .getProductId();
+        
+        order.removeOrder(productId);
 
         assertEquals(0, order
           .getOrderItems()

ddd/src/test/java/com/baeldung/ddd/layers/domain/service/DomainOrderServiceUnitTest.java

@@ -80,8 +80,8 @@ class DomainOrderServiceUnitTest {
         final UUID productId = order
           .getOrderItems()
           .get(0)
-          .getProduct()
-          .getId();
+          .getProductId();
+        
         when(orderRepository.findById(order.getId())).thenReturn(Optional.of(order));
 
         tested.deleteProduct(order.getId(), productId);