public function sendToUser(
        SystemNotification $notification,
        DataObject $context,
        $user,
        $extraData = []
    ) {
        $channels = $this->channels;
        if ($extraData && isset($extraData['SEND_CHANNELS'])) {
            $channels = $extraData['SEND_CHANNELS'];
            unset($extraData['SEND_CHANNELS']);
        }

        if (!is_array($channels)) {
            $channels = [$channels];
        }

        foreach ($channels as $channel) {
            if ($sender = $this->getSender($channel)) {
                $sender->sendToUser($notification, $context, $user, $extraData);
            }
        }
    }