no-interface.php

/**
 * @Route("/foo/{bar}/{baz}")
 */
class SomePage extends ControllerBase {

  /**
   * @Content
   */
  public function content(NodeInterface $bar, UserInterface $baz) {
    return 'Blaaah';
  }

  /**
   * @Title
   */
  public function title(NodeInterface $bar, UserInterface $baz) {
    return 'Meeeh';
  }

}