@Override
    public void stop()
    {
        if (expiryCheckerTask != null) {
            TaskEngine.getInstance().cancelScheduledTask(expiryCheckerTask);
            expiryCheckerTask = null;
        }
    }
How long before a TLS certificate will expire a warning is to be sent out to admins.
xmppserver/src/main/java/org/jivesoftware/util/cert/CertificateExpiryChecker.java