public BookOutlineForm::save(array $form, FormStateInterface

The book manager. Type:

Provides methods for exporting book to different formats. If you would like to add another format, swap this class in container.

BookManager service. Type:

public BookManager::getParentDepthLimit(array $book_link)

public BookExport::bookExportHtml(NodeInterface $node)

public BookOutlineForm::__construct(EntityManagerInterface

Config Factory Service Object. Type:

Defines the maximum supported depth of the book tree. File core/modules/book/src/BookManager.php, line

public BookOutlineStorage::getBookSubtree($link, $max_depth)