ui_icons-1.0.x-dev/ui_icons.routing.yml

ui_icons.autocomplete:
  path: '/ui-icons/ajax/autocomplete/icons'
  defaults:
    _controller: '\Drupal\ui_icons\Controller\IconAutocompleteController::handleSearchIcons'
  requirements:
    _permission: 'access content'

ui_icons.preview:
  path: '/ui-icons/ajax/preview/icons'
  defaults:
    _controller: '\Drupal\ui_icons\Controller\IconPreviewController::preview'
  requirements:
    _permission: 'access content'
    _method: 'POST'