ckeditor5-1.0.x-dev/ckeditor5.services.yml

services:
  plugin.manager.ckeditor5.plugin:
    class: Drupal\ckeditor5\Plugin\CKEditor5PluginManager
    parent: default_plugin_manager
  ckeditor5.admin_ui:
    class: Drupal\ckeditor5\AdminUi
    arguments:
      - '@plugin.manager.ckeditor5.plugin'