* @param oc the session ref to the target db to clear
*/
private static void clearDb4oDb(ObjectContainer oc) {
if(oc == null) return;
final ExtObjectContainer s = oc.ext();
final ReflectClass[] rcs = s.knownClasses();
if(rcs != null) {
for(final ReflectClass rc : rcs) {
if(rc.getDelegate() instanceof JdkClass) {
final Class<?> objType = ((JdkClass) rc.getDelegate()).getJavaClass();
final String cn = objType.getName();