custom_elements-8.x-2.x-dev/modules/custom_elements_ui/custom_elements_ui.services.yml

services:
  custom_elements_ui.subscriber:
    class: Drupal\custom_elements_ui\Routing\RouteSubscriber
    arguments: [ '@entity_type.manager' ]
    tags:
      - { name: event_subscriber }
  access_check.custom_elements_ui.view_mode:
    class: Drupal\custom_elements_ui\Access\CustomElementViewModeAccessCheck
    arguments: [ '@entity_type.manager' ]
    tags:
      - { name: access_check, applies_to: _custom_elements_ui_view_mode_access }