Issue with WP Example about wp-update-server HOT 5 CLOSED

require_once __DIR__ . '/path/to/wp-update-server/loader.php';

class Wpup_UpdateServer_Extension extends Wpup_UpdateServer {
    // Change the action and slug to match others
    protected function generateDownloadUrl(Wpup_Package $package) {
        $query = array(
            'update_action' => 'download',
            'update_slug' => $package->slug,
        );
        return self::addQueryArg($query, $this->serverUrl);
    }
}

class ExamplePlugin {
    protected $updateServer;

    public function __construct() {
        $this->updateServer = new Wpup_UpdateServer_Extension(home_url('/'));
        add_filter('query_vars', array($this, 'addQueryVariables'));
        add_action('template_redirect', array($this, 'handleUpdateApiRequest'));
    }

    public function addQueryVariables($queryVariables) {
        $queryVariables = array_merge($queryVariables, array(
            'update_action',
            'update_slug',
        ));
        return $queryVariables;
    }

    public function handleUpdateApiRequest() {
        if ( get_query_var('update_action') ) {
            $this->updateServer->handleRequest(array(
                'action' => get_query_var('update_action'),
                'slug'   => get_query_var('update_slug'),
            ));
        }
    }
}

$examplePlugin = new ExamplePlugin();