It is possible to create a class hierarchy by executing the following commands:
All classes are annotated by @Entity and this implies @Inheritance(strategy=InheritanceType.SINGLE_TABLE).
In many cases this is not suitable.
So it would be nice to have a parameter '--inheritanceStrategy' (in case '--abstract' is used, too). This could have values like 'SINGLE_TABLE', 'JOINED' or 'MAPPED_SUPERCLASS'.