title: EclipseLink JPA inheritance without discriminator column
body: <p>I have a Client and Affiliate class, inheriting from Person class. Joined inheritance strategy type is being used - each of them sharing primary key with the parent class. As there's no discriminator column we chose to use <a href="http://wiki.eclipse.org/EclipseLink/UserGuide/JPA/Basic_JPA_Development/Entities/Inheritance#.40ClassExtractor" rel="nofollow">DescriptorCustomizer and ClassExtractor</a>. But it doesn't really give any idea how it works, also, the code doesnt seem to compile. It would be nice if someone gives a nice example with code snippet for understanding.</p>