return buf.toString();
    }

    protected void sendToGoogleChat(final CardView cardView, final SMailPostingDiscloser discloser) {
        // https://developers.google.com/hangouts/chat/how-tos/webhooks
        final FessConfig fessConfig = ComponentUtil.getFessConfig();
        final String googleChatWebhookUrls = fessConfig.getGoogleChatWebhookUrls();
        if (StringUtil.isBlank(googleChatWebhookUrls)) {