private JMXConnector setUpConnection(String server, int jmxPort) {

    try {

        Registry r = LocateRegistry.getRegistry(server, jmxPort);

        HashMap<String, Object> env = new HashMap<String, Object>();

        String[] credentials = {"username", "password"};
        env.put(JMXConnector.CREDENTIALS, credentials);
        env.put("com.sun.jndi.rmi.factory.socket", new SslRMIClientSocketFactory());  // uncomment if needed


                JMXServiceURL url = new JMXServiceURL("service:jmx:rmi:///jndi/rmi://" + server + ":" + jmxPort + "/jmxrmi");
        return JMXConnectorFactory.newJMXConnector(url, env);

    } catch (Exception e) {
        e.printStackTrace();
    }
    return null;

}

java.io.IOException: Failed to retrieve RMIServer stub: javax.naming.CommunicationException [Root exception is java.rmi.ConnectIOException: error during JRMP connection establishment; nested exception is:
    javax.net.ssl.SSLHandshakeException: Remote host closed connection during handshake]

env.put("com.sun.jndi.rmi.factory.socket", new SslRMIClientSocketFactory());

env.put("com.sun.jndi.rmi.factory.socket", new SslRMIClientSocketFactory());