Let's say i have an entity Product which has some kind of reference to entity Invoice. To simplify things: Let's say an Invoice can only reference one Product (OneToOne Association).
But i can't use a simple Association, because the Product properties might change during usage of the application and those changes should not impact the Invoice.
So, everytime i want to associate an Product with an Invoice, i should clone the Product and have some kind of revision entity: ProductRevision extends Product. But Product has some other associated entities, which have to revisioned, too.
Any ideas how to implement this nicely?