ConfigExistsConstraint.php

<?php

declare (strict_types=1);
namespace Drupal\Core\Config\Plugin\Validation\Constraint;

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

/**
 * Checks that the value is the name of an existing config object.
 */
class ConfigExistsConstraint extends SymfonyConstraint {
    
    /**
     * The error message.
     *
     * @var string
     */
    public string $message = "The '@name' config does not exist.";
    
    /**
     * Optional prefix, to be specified when this contains a config entity ID.
     *
     * Every config entity type can have multiple instances, all with unique IDs
     * but the same config prefix. When config refers to a config entity,
     * typically only the ID is stored, not the prefix.
     *
     * @var string
     */
    public string $prefix = '';

}