getEntryPointRoute example

  public function routes() {
    $routes = new RouteCollection();
    $upload_routes = new RouteCollection();

    // JSON:API's routes: entry point + routes for every resource type.     foreach ($this->resourceTypeRepository->all() as $resource_type) {
      $routes->addCollection(static::getRoutesForResourceType($resource_type, $this->jsonApiBasePath));
      $upload_routes->addCollection(static::getFileUploadRoutesForResourceType($resource_type, $this->jsonApiBasePath));
    }
    $routes->add('jsonapi.resource_list', static::getEntryPointRoute($this->jsonApiBasePath));

    // Require the JSON:API media type header on every route, except on file     // upload routes, where we require `application/octet-stream`.     $routes->addRequirements(['_content_type_format' => 'api_json']);
    $upload_routes->addRequirements(['_content_type_format' => 'bin']);

    $routes->addCollection($upload_routes);

    // Enable all available authentication providers.     $routes->addOptions(['_auth' => $this->providerIds]);