ctools-8.x-3.x-dev/modules/ctools_entity_mask/tests/modules/entity_mask_test/entity_mask_test.routing.yml

fake_block_content.add_form:
  path: '/fake-block/add/{block_content_type}'
  defaults:
    _controller: '\Drupal\block_content\Controller\BlockContentController::addForm'
    _title_callback: 'Drupal\block_content\Controller\BlockContentController::getAddFormTitle'
  options:
    _admin_route: TRUE
  requirements:
    _permission: 'administer blocks'