Assume the following code:
Bootstrapping an EntityManager for those types and trying to look up the type of the identifier property for ConcreteEntity returns Serializable instead of Long.
Find a reproducing example in this commit. Steps to reproduce:
The build uses Hibernate 5.1 by default but the version can be tweaked by using the profiles declared in the parent POM.
I had the same problem with property-accessors. A workaround for the property case would be to define the concrete methods in the concrete class and annotate them again.
Still present in the just released 5.2.1.