This empty class is the common root for all persistent capable classes.
If this class inherits from java.lang.Object
then all subclasses are serializable with
the standard Java serialization mechanism.
If this class inherits from com.objy.db.app.ooObj
then all subclasses are
serializable with the Objectivity ODBMS persistance mechanism.
Thus, by modifying the inheritance of this class the entire tree of subclasses can
be switched to Objectivity compatibility (and back) with minimum effort.