EntityTypeConstraint.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;

/**
 * Checks if a value is a valid entity type.
 */
class EntityTypeConstraint extends SymfonyConstraint {
  public function __construct(public string $type, public $message = 'The entity must be of type %type.', ?array $groups = NULL, mixed $payload = NULL) {
    parent::__construct(groups: $groups, payload: $payload);
  }

}