bigmenu.routing.yml

bigmenu.menu:
  path: '/admin/structure/menu/manage/{menu}/bigmenu'
  defaults:
    _entity_form: 'menu.edit_bigmenu'
    _title_callback: '\Drupal\menu_ui\Controller\MenuController::menuTitle'
  requirements:
    _entity_access: 'menu.update'
    _permission: 'use bigmenu'

bigmenu.menu_link:
  path: 'admin/structure/menu/manage/{menu}/bigmenu/link/{menu_link}'
  defaults:
    _title: 'Edit a slice of a menu'
    _entity_form: 'menu.edit_bigmenu_slice'
  requirements:
    _entity_access: 'menu.update'
    _permission: 'use bigmenu'

#bigmenu.menu_link_js:
#  path: 'admin/structure/menu/manage/{menu}/bigmen/link/{menu_link}/js'
#  defaults:
#    _title: 'Edit a slice of a menu'
#    _controller: '\Drupal\bigmenu\Controller\JsSliceController::getChildren'
#  requirements:
#    #_entity_access: 'menu.update'
#    _permission: 'use bigmenu'

#bigmenu.settings:
#  defaults:
#    _title: 'Big Menu Settings'
#    _description: 'Configure settings for bigmenu module.'
#  requirements:
#    _permission: 'administer bigmenu'