protected function isRootTypeNode(ObjectId $oid) {
    if ($oid->containsDummyIds()) {
      $type = $oid->getType();
      $rootTypes = $this->getRootTypes();
      foreach ($rootTypes as $rootType) {
        if ($rootType->getType() == $type) {
          return true;
        }
      }
    }
    return false;
  }