@Override
    public void start() {
        super.start();
        startListeners();
        CertificateManager.addListener(this);
    }
Sets the TCP port on which a listener accepts connections.

@param type The connection type for which a listener is to be configured.
@param startInDirectTlsMode true when the listener to be configured is in Direct TLS mode, otherwise false.
@param port a port number.
xmppserver/src/main/java/org/jivesoftware/openfire/spi/ConnectionManagerImpl.java