ToolbarItemConstraint.php

<?php

declare (strict_types=1);
namespace Drupal\ckeditor5\Plugin\Validation\Constraint;

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

/**
 * A CKEditor 5 toolbar item.
 *
 * @see https://ckeditor.com/docs/ckeditor5/latest/features/toolbar/toolbar.html
 */
class ToolbarItemConstraint extends SymfonyConstraint {
    
    /**
     * The default violation message.
     *
     * @var string
     */
    public $message = 'The provided toolbar item %toolbar_item is not valid.';

}