Gets the unrouted URL assembler for non-Drupal URLs.
\Drupal\Core\Utility\UnroutedUrlAssemblerInterface The unrouted URL assembler.
protected function unroutedUrlAssembler() { if (!$this->urlAssembler) { $this->urlAssembler = \Drupal::service('unrouted_url_assembler'); } return $this->urlAssembler; }