WorkspacePrePublishEvent example

  public function publish() {
    if ($this->sourceWorkspace->hasParent()) {
      throw new WorkspacePublishException('Only top-level workspaces can be published.');
    }

    if ($this->checkConflictsOnTarget()) {
      throw new WorkspaceConflictException();
    }

    $tracked_entities = $this->workspaceAssociation->getTrackedEntities($this->sourceWorkspace->id());
    $event = new WorkspacePrePublishEvent($this->sourceWorkspace, $tracked_entities);
    $this->eventDispatcher->dispatch($event);

    if ($event->isPublishingStopped()) {
      throw new WorkspacePublishException((string) $event->getPublishingStoppedReason());
    }

    try {
      $transaction = $this->database->startTransaction();
      // @todo Handle the publishing of a workspace with a batch operation in       // https://www.drupal.org/node/2958752.       $this->workspaceManager->executeOutsideWorkspace(function D) use ($tracked_entities) {