piwik-8.x-1.4/tests/modules/piwik_test/piwik_test.routing.yml

piwik_test.drupal_set_message:
  path: '/piwik-test/drupal-set-message'
  defaults:
    _title: 'Set messages with drupal_set_message()'
    _controller: '\Drupal\piwik_test\Controller\PiwikTestController::drupalSetMessageTest'
  requirements:
    _access: 'TRUE'