EntityManager.find ClassCastException for wrong but existing id

Hello,

I have base entity and 2 inheritors e.g. Person and Document.
If I try to find Person entity and provide id of the Document entity I get
ClassNotFoundException but it should return either null or
EntityNotFoundException.
If I provide just some wrong non existing id I get null.
Here is link to the maven project with test: openjpa-find-test.zip
<http://openjpa.208410.n2.nabble.com/file/n7587085/openjpa-find-test.zip>
Should I post a bug in issue tracker?

Thanks,
Oleg