class EntityReferenceSupportedNewEntitiesConstraintValidator

class EntityReferenceSupportedNewEntitiesConstraintValidator extends ConstraintValidator implements ContainerInjectionInterface {
  
  /**
   * The workspace manager.
   *
   * @var \Drupal\workspaces\WorkspaceManagerInterface
   */
  protected $workspaceManager;
  
  /**
   * The entity type manager.
   *
   * @var \Drupal\Core\Entity\EntityTypeManagerInterface
   */
  protected $entityTypeManager;
  
  /**
   * The workspace information service.
   *
   * @var \Drupal\workspaces\WorkspaceInformationInterface
   */
  protected $workspaceInfo;
  
  /**
   * Creates a new EntityReferenceSupportedNewEntitiesConstraintValidator instance.
   */
  public function __construct(WorkspaceManagerInterface $workspaceManager, EntityTypeManagerInterface $entityTypeManager, WorkspaceInformationInterface $workspace_information) {
    $this->workspaceManager = $workspaceManager;
    $this->entityTypeManager = $entityTypeManager;
    $this->workspaceInfo = $workspace_information;
  }
  
  /**
   * {@inheritdoc}
   */
  public static function create(ContainerInterface $container) {
    return new static($container->get('workspaces.manager'), $container->get('entity_type.manager'), $container->get('workspaces.information'));
  }
  
  /**
   * {@inheritdoc}
   */
  public function validate($value, Constraint $constraint) {
    // The validator should run only if we are in a active workspace context.
    if (!$this->workspaceManager
      ->hasActiveWorkspace()) {
      return;
    }
    $target_entity_type_id = $value->getFieldDefinition()
      ->getFieldStorageDefinition()
      ->getSetting('target_type');
    $target_entity_type = $this->entityTypeManager
      ->getDefinition($target_entity_type_id);
    if ($value->hasNewEntity() && !$this->workspaceInfo
      ->isEntityTypeSupported($target_entity_type)) {
      $this->context
        ->addViolation($constraint->message, [
        '%collection_label' => $target_entity_type->getCollectionLabel(),
      ]);
    }
  }

}