Mihalcea Vlad commented on an issue
Hibernate ORM / Bug HHH-8618
When the PersistentSet is loaded from database, it can't find it's contained elements.
My use case is very simple, and it goes like this:

A have a Product parent association and an Image child association.
Product contains a Set<Image>.

Here is what I did:

Product product = entityManager.find(Product.class, productId);
assertEquals(2, product.getImages().size());
Iterator<Image> imageIterator = product.getImages().iterator();
...