@Override
 public Key[] listKeys(ObjectContainer container) {
   boolean activated = false;
   if (persistent) {
     activated = container.ext().isActive(segment);
     if (!activated) container.activate(segment, 1);
   }
   Key[] keys = segment.listKeys(container);
   if (persistent && !activated) container.deactivate(segment, 1);
   return keys;
 }