examples-3.x-dev/modules/events_example/events_example.routing.yml

# Define a route for our event dispatching example.
events_example.description:
  path: '/examples/events-example'
  defaults:
    _form: '\Drupal\events_example\Form\EventsExampleForm'
    _title: 'Events Example'
  requirements:
    _permission: 'access content'