outline-8.x-1.x-dev/tests/modules/outline_serialization_test/outline_serialization_test.routing.yml

outline_serialization_test:
  path: '/outline_serialization_test/{outline}'
  defaults:
    _controller: '\Drupal\outline_serialization_test\OutlineSerializationTestController::outlineResponse'
  requirements:
    _access: 'TRUE'