examples-3.x-dev/modules/menu_example/menu_example.services.yml

services:
  menu_example.access_check.role:
    class: Drupal\menu_example\Access\RoleAccessCheck
    arguments: ['@current_user']
    tags:
      # _menu_example_role is added to the requirements section in the
      # menu_example.routing.yml file to apply a custom access checker.
      - { name: access_check, applies_to: _menu_example_role }
  menu_example.route_subscriber:
    class: Drupal\menu_example\Routing\RouteSubscriber
    tags:
      - { name: event_subscriber }