protected function GenerateAndroidPinicon(SiteConfig $config, SiteTree $owner, &$metadata) {

        // header
        $metadata .= $owner->MarkupComment('Android Pinned Icon');

        //
        if ($config->fetchAndroidPiniconThemeColor()) {
            $metadata .= $owner->MarkupMeta('theme-color', $config->fetchAndroidPiniconThemeColor());
        }

        //
        $metadata .= $owner->MarkupLink('manifest', '/manifest.json');

    }