public BookOutlineStorageInterface::getBookMenuTree($bid

book_node_builder($entity_type, NodeInterface $entity, &$form, FormStateInterface $form_state) Entity form

Defines a common interface for book outline storage classes. Hierarchy interface \Drupal\book\

public BookManager::__construct(EntityManagerInterface $entity_manager,

Provides a breadcrumb builder for nodes in a book. Hierarchy class \Drupal\book\

protected BookSettingsForm::getEditableConfigNames()