Implements hook_theme().
public function theme($existing, $type, $theme, $path) : array { $items['toolbar'] = [ 'render element' => 'element', ]; $items['menu__toolbar'] = [ 'base hook' => 'menu', 'variables' => [ 'menu_name' => NULL, 'items' => [], 'attributes' => [], ], ]; return $items; }