@Override
    public void start() throws IllegalStateException
    {
        expiryCheckerTask = new ExpiryCheckerTask();
        TaskEngine.getInstance().schedule(expiryCheckerTask, Duration.ofSeconds(20), FREQUENCY.getValue());
    }
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