@Test
 public void testFunctionalMultiValueAttribute() {
   MultiValueAttribute<Car, String> CAR_ID = attribute(String.class, featuresFunction);
   assertEquals(Car.class, CAR_ID.getObjectType());
   assertEquals(String.class, CAR_ID.getAttributeType());
   assertTrue(CAR_ID.getAttributeName().startsWith(this.getClass().getName() + "$"));
 }
 @Test
 public void testFunctionalSimpleNullableAttribute() {
   SimpleNullableAttribute<Car, Integer> CAR_ID = nullableAttribute(carIdFunction);
   assertEquals(Car.class, CAR_ID.getObjectType());
   assertEquals(Integer.class, CAR_ID.getAttributeType());
   assertTrue(CAR_ID.getAttributeName().startsWith(this.getClass().getName() + "$"));
 }