protected function getViewNode(Node $node, $displayText='') {
    if (strlen($displayText) == 0) {
      $displayText = trim($this->getDisplayText($node));
    }
    if (strlen($displayText) == 0) {
      $displayText = '-';
    }
    $oid = $node->getOID();
    $isFolder = $oid->containsDummyIds();
    $hasChildren = $this->isRootTypeNode($oid) || sizeof($node->getNumChildren()) > 0;
    return [
      'oid' => $node->getOID()->__toString(),
      'displayText' => $displayText,
      'isFolder' => $isFolder,
      'hasChildren' => $hasChildren
    ];
  }