docs: private void ensureReferencedPKs(ModelDef modelDef, ReferenceDescriptorDef refDef) throws ConstraintException
      {
          String             targetClassName = refDef.getProperty(PropertyHelper.OJB_PROPERTY_CLASS_REF);
          ClassDescriptorDef targetClassDef  = modelDef.getClass(targetClassName);
  
          ensurePKsFromHierarchy(targetClassDef);
      }