super.setUp();
        notificationHelper = new NotificationHelper();
    }

    public void test_sendToSlack_withBlankWebhookUrls() {
        // Setup mock configuration with blank webhook URLs
        ComponentUtil.setFessConfig(new MockFessConfig() {
            @Override
            public String getSlackWebhookUrls() {
                return "";
            }
        });

    /** Property key for Slack webhook URLs configuration. */
    public static final String SLACK_WEBHOOK_URLS_PROPERTY = "slack.webhook.urls";

    /** Property key for Google Chat webhook URLs configuration. */
    public static final String GOOGLE_CHAT_WEBHOOK_URLS_PROPERTY = "google.chat.webhook.urls";

    /** Property key for browser locale usage in search configuration. */

* Audit events now log the existence and patch of mutating webhooks.  ([#77824](https://github.com/kubernetes/kubernetes/pull/77824), [@roycaihw](https://github.com/roycaihw))
        * At Metadata audit level or higher, an annotation with key "mutation.webhook.admission.k8s.io/round_{round idx}_index_{order idx}" gets logged with JSON payload indicating a webhook gets invoked for given request and whether it mutated the object or not.

- Changed apiserver to treat failures decoding a mutating webhook patch as failures to call the webhook so they trigger the webhook failurePolicy and count against metrics like `webhook_fail_open_count` ([#131627](https://github.com/kubernetes/kubernetes/pull/131627), [@dims](https://github.com/dims)) [SIG API Machinery]

- Added support for CEL expressions to `v1alpha1 AuthorizationConfiguration` webhook `matchConditions`. ([#121223](https://github.com/kubernetes/kubernetes/pull/121223), [@ritazh](https://github.com/ritazh))

- Kube-apiserver: timeouts configured for authorization webhooks in the --authorization-config file are now honored, and webhook timeouts are accurately reflected in webhook metrics with result=timeout ([#125552](https://github.com/kubernetes/kubernetes/pull/125552), [@liggitt](https://github.com/liggitt)) [SIG API Machinery, Auth and Testing]

- kube-apiserver: Promoted `AuthorizeWithSelectors` feature to beta, which includes field and label selector information from requests in webhook authorization calls. Promoted `AuthorizeNodeWithSelectors` feature to beta, which changes node authorizer behavior to limit requests from node API clients, so that each Node can only get / list / watch its own Node API object, and can also only get...

- Ignore context canceled from validate and mutate webhook ([#120155](https://github.com/kubernetes/kubernetes/pull/120155), [@divyasri537](https://github.com/divyasri537)) [SIG API Machinery]

   ([#121946](https://github.com/kubernetes/kubernetes/pull/121946), [@liggitt](https://github.com/liggitt))

     * @param discloser the mail posting discloser
     */
    protected void sendToSlack(final CardView cardView, final SMailPostingDiscloser discloser) {
        // https://api.slack.com/messaging/webhooks#posting_with_webhooks
        final FessConfig fessConfig = ComponentUtil.getFessConfig();
        final String slackWebhookUrls = fessConfig.getSlackWebhookUrls();
        if (StringUtil.isBlank(slackWebhookUrls)) {