Piwik\Notification\Manager::addNotification PHP Method

    private static function addNotification($id, Notification $notification)
    {
        self::saveNotificationAcrossUiRequestsIfNeeded($id, $notification);
        // we store all kinda notifications here so in case the session is not enabled or disabled later there is still
        // a chance it gets delivered to the UI during the same request.
        self::$notifications[$id] = $notification;
    }