ReferenceAccessConstraint.php

<?php

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

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

/**
 * Entity Reference valid reference constraint.
 *
 * Verifies that referenced entities are valid.
 */
class ReferenceAccessConstraint extends SymfonyConstraint {
    
    /**
     * The default violation message.
     *
     * @var string
     */
    public $message = 'You do not have access to the referenced entity (%type: %id).';

}