custom_formatters.routing.yml

custom_formatters.add_page:
  path: '/admin/structure/formatters/add'
  defaults:
    _title: 'Add formatter'
    _controller: '\Drupal\custom_formatters\Controller\CustomFormattersController::addList'
  requirements:
    _permission: 'administer custom formatters'

custom_formatters.add:
  path: '/admin/structure/formatters/add/{formatter_type}'
  defaults:
    _title: 'Add formatter'
    _controller: '\Drupal\custom_formatters\Controller\CustomFormattersController::add'
  requirements:
    _permission: 'administer custom formatters'

custom_formatters.settings_form:
  path: '/admin/structure/formatters/settings'
  defaults:
    _form: '\Drupal\custom_formatters\Form\CustomFormattersSettingsForm'
    _title: 'Settings'
  requirements:
    _permission: 'administer custom formatters'

entity.formatter.collection:
  path: '/admin/structure/formatters'
  defaults:
    _entity_list: 'formatter'
    _title: 'Formatters'
  requirements:
    _permission: 'administer custom formatters'

entity.formatter.edit_form:
  path: '/admin/structure/formatters/manage/{formatter}'
  defaults:
    _entity_form: 'formatter.edit'
    _title_callback: 'Drupal\custom_formatters\Controller\CustomFormattersController::editTitle'
  requirements:
    _entity_access: 'formatter.update'

entity.formatter.delete_form:
  path: '/admin/structure/formatters/manage/{formatter}/delete'
  defaults:
    _entity_form: 'formatter.delete'
    _title: 'Delete'
  requirements:
    _entity_access: 'formatter.delete'