Can you have a @MappedSuperclass annotation on a baseClass that has an Id property and the super classes will just override the getId() method to have the @Id annotation?

I do not think it works, I don't understand why it is useful either :-)

The reason why i wantedt this is because I want to define an abstract PersistableClass that has a Long getId() and all my persistable classes subclass this base class.

I have managed to get it working but I had to put @MappedSuperClass on the abstract class and marked the getId() as @Transient. On the subclasses they override the getId() method and has the @Id annotation

If your Id is a Long, just add the property with its setter/getter and annotations in you base class (annotated with MappedSuperClass). In your subclass no nedd to take care about the Id anymore.

I used it, and it works fine.

I never unerstood the benefit of a PersistentClass superclass, if you really need such things, use an Interface.

I have an interface with 2 methods getId and getVersion.

In most of my classes, id is generated and version is just a long annotated with version. In thta case, the superclass is just a convenient way not to rewritte in all my classes the version and the id.

Moreover, most of my persistent entites will never goes in a transient map or collections. In my superclass I wrotte a equals and hashcode based on the value of the id (risks of doing such impl is discussed on the wiki).