service theme.negotiator.theme_switcher_negotiator in Theme Switcher Rules 8

class: Drupal\theme_switcher\Theme\ThemeSwitcherNegotiator
arguments:
  - '@router.admin_context'
  - '@entity_type.manager'
  - '@context.handler'
  - '@context.repository'
tags:
  - { name: theme_negotiator, priority: 12 }