EntityTestRoutes.php

<?php

namespace Drupal\entity_test\Routing;

use Symfony\Component\Routing\Route;

/**
 * Subscriber for Entity Test routes.
 */
class EntityTestRoutes {
  
  /**
   * Returns an array of route objects.
   *
   * @return \Symfony\Component\Routing\Route[]
   *   An array of route objects.
   */
  public function routes() {
    $types = entity_test_entity_types(ENTITY_TEST_TYPES_ROUTING);
    $routes = [];
    foreach ($types as $entity_type_id) {
      $routes["entity.{$entity_type_id}.admin_form"] = new Route("{$entity_type_id}/structure/{bundle}", [
        '_controller' => '\\Drupal\\entity_test\\Controller\\EntityTestController::testAdmin',
      ], [
        '_permission' => 'administer entity_test content',
      ], [
        '_admin_route' => TRUE,
      ]);
    }
    return $routes;
  }

}