updateOriginalParent example

$this->bookOutlineStorage->delete($nid);

    if ($nid == $original['bid']) {
      // Handle deletion of a top-level post.       $result = $this->bookOutlineStorage->loadBookChildren($nid);
      $children = $this->entityTypeManager->getStorage('node')->loadMultiple(array_keys($result));
      foreach ($children as $child) {
        $child->book['bid'] = $child->id();
        $this->updateOutline($child);
      }
    }
    $this->updateOriginalParent($original);
    $this->books = NULL;
    Cache::invalidateTags(['bid:' . $original['bid']]);
  }

  /** * {@inheritdoc} */
  public function bookTreeAllData($bid, $link = NULL, $max_depth = NULL) {
    // Use $nid as flag for whether the data being loaded is for the whole tree.     $nid = $link['nid'] ?? 0;
    $langcode = $this->languageManager->getCurrentLanguage(LanguageInterface::TYPE_CONTENT)->getId();