use Drupal\Core\StringTranslation\StringTranslationTrait;
use Symfony\Component\DependencyInjection\ContainerInterface;
use Symfony\Component\HttpFoundation\RequestStack;
+use Drupal\Core\Messenger\MessengerTrait;
/**
* Provides a base class for forms.
use DependencySerializationTrait;
use LinkGeneratorTrait;
use LoggerChannelTrait;
+ use MessengerTrait;
use RedirectDestinationTrait;
use StringTranslationTrait;
use UrlGeneratorTrait;