CMP 1.x beans with complex keys can generate an incorrect JPA mapping.

The code that generates the JPA mapped superclasses for CMP 1.x entity beans can create an incorrect mapping if the beans use complex keys and the key fields are implemented on different subclasses of the hierarchy. In this situation, one of the subclasses is identified as the idClass(). If the subclass chosen happens to be the most-derived type, then the mapping will be correct. Any other choice will generate an incorrect mapping. This code needs to ensure that the most-derived type gets marked.