ValidPathConstraint.php

<?php

namespace Drupal\Core\Path\Plugin\Validation\Constraint;

use Drupal\Core\StringTranslation\TranslatableMarkup;
use Drupal\Core\Validation\Attribute\Constraint;
use Symfony\Component\Validator\Constraint as SymfonyConstraint;

/**
 * Validation constraint for valid system paths.
 */
class ValidPathConstraint extends SymfonyConstraint {
    
    /**
     * The default violation message.
     *
     * @var string
     */
    public $message = "Either the path '%link_path' is invalid or you do not have access to it.";

}