phorge-phorge/src/applications/flag/controller/PhabricatorFlagController.php

<?php

abstract class PhabricatorFlagController extends PhabricatorController {

  public function buildSideNavView() {
    $user = $this->getRequest()->getUser();

    $nav = new AphrontSideNavFilterView();
    $nav->setBaseURI(new PhutilURI($this->getApplicationURI()));

    id(new PhabricatorFlagSearchEngine())
      ->setViewer($user)
      ->addNavigationItems($nav->getMenu());

    $nav->selectFilter(null);

    return $nav;
  }

}