name : MetadataHeader.php <?php /* * This file is part of the Symfony package. * * (c) Fabien Potencier <fabien@symfony.com> * * For the full copyright and license information, please view the LICENSE * file that was distributed with this source code. */ namespace Symfony\Component\Mailer\Header; use Symfony\Component\Mime\Header\UnstructuredHeader; /** * @author Kevin Bond <kevinbond@gmail.com> */ final class MetadataHeader extends UnstructuredHeader { public function __construct( private string $key, string $value, ) { parent::__construct('X-Metadata-'.$key, $value); } public function getKey(): string { return $this->key; } }