ckeditor_mentions.routing.yml

ckeditor_mentions.ajax_callback:
  path: '/ckeditor-mentions/ajax/{plugin_id}/{match}'
  defaults:
    _controller: 'Drupal\ckeditor_mentions\Controller\CKMentionsController::getMatch'
    _title: 'Retrieve realname match'
    match: ''
    plugin_id: '[^a-z0-9_]+'
  methods: [GET]
  requirements:
    _permission: 'use inline mentions'