MockSMailPostingDiscloser discloser = new MockSMailPostingDiscloser();
        discloser.setSubject("Test Subject");
        discloser.setPlainText("Test Content");

        String result = notificationHelper.toSlackMessage(discloser);

        assertNotNull(result);
        assertTrue(result.contains("Test Subject"));
        assertTrue(result.contains("Test Content"));
        assertTrue(result.startsWith("{\"text\":\""));

        final String slackWebhookUrls = fessConfig.getSlackWebhookUrls();
        if (StringUtil.isBlank(slackWebhookUrls)) {
            return;
        }
        final String body = toSlackMessage(discloser);
        StreamUtil.split(slackWebhookUrls, "[,\\s]").of(stream -> stream.filter(StringUtil::isNotBlank).forEach(url -> {