class DeletedWorkspaceConstraintValidator

class DeletedWorkspaceConstraintValidator extends ConstraintValidator implements ContainerInjectionInterface {
    
    /**
     * The state service.
     *
     * @var \Drupal\Core\State\StateInterface
     */
    protected $state;
    
    /**
     * Creates a new DeletedWorkspaceConstraintValidator instance.
     *
     * @param \Drupal\Core\State\StateInterface $state
     *   The state service.
     */
    public function __construct(StateInterface $state) {
        $this->state = $state;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function create(ContainerInterface $container) {
        return new static($container->get('state'));
    }
    
    /**
     * {@inheritdoc}
     */
    public function validate($value, Constraint $constraint) {
        
        /** @var \Drupal\Core\Field\FieldItemListInterface $value */
        // This constraint applies only to newly created workspace entities.
        if (!isset($value) || !$value->getEntity()
            ->isNew()) {
            return;
        }
        $deleted_workspace_ids = $this->state
            ->get('workspace.deleted', []);
        if (isset($deleted_workspace_ids[$value->getEntity()
            ->id()])) {
            $this->context
                ->addViolation($constraint->message);
        }
    }

}