FieldConfigListController.php

<?php

namespace Drupal\field_ui\Controller;

use Drupal\Core\Entity\Controller\EntityListController;
use Drupal\Core\Routing\RouteMatchInterface;

/**
 * Defines a controller to list field instances.
 */
class FieldConfigListController extends EntityListController {
    
    /**
     * Shows the 'Manage fields' page.
     *
     * @param string $entity_type_id
     *   The entity type.
     * @param string $bundle
     *   The entity bundle.
     * @param \Drupal\Core\Routing\RouteMatchInterface $route_match
     *   The current route match.
     *
     * @return array
     *   A render array as expected by
     *   \Drupal\Core\Render\RendererInterface::render().
     */
    public function listing($entity_type_id = NULL, $bundle = NULL, ?RouteMatchInterface $route_match = NULL) {
        return $this->entityTypeManager()
            ->getListBuilder('field_config')
            ->render($entity_type_id, $bundle);
    }

}