How to publish to MQTT using paho in Spring Boot

Question

I want to publish an MQTT message using Eclipse's Paho library, but EOFException and connection lost exceptions are occurring. I have tried changing the broker url to ssl or tcp but neither are working. There are 2 methods which I have written. One is working fine, but the second one with Paho is not working, and I want subscribe using Paho. What's wrong with my code?

Below 1st method is working fine:

String clientEndPoint = "sedhhytjkss-ats.iot.ap-southeast-1.amazonaws.com";
String clientId = "smart_pen";
String awsAccessKeyId = "DRSFGDFKLSLDSP";
String awsSecretAccessKey = "/HHJKlkKLDddkdldsksdpsk255s6";

@GetMapping("/")
public void publishMessage() throws IOException, AWSIotException {
    String topic = "$aws/things/smart_pen/shadow/update";
    String state = "{\"state\":{\"reported\":{\"smart_pen\":3.0}}}";
    AWSIotQos qos = AWSIotQos.QOS0;
    String payload = "first message";
    long timeout = 3000;

    AWSIotMqttClient client = new AWSIotMqttClient(clientEndPoint, clientId,
            awsAccessKeyId, awsSecretAccessKey,
            null);
    AWSIotDevice device = new AWSIotDevice(clientId);
    client.attach(device);
    client.connect();

    MyMessage message = new MyMessage(topic, qos, payload.toString());
    client.publish(message, timeout);
}

The below 2nd method not working :

private static final String BROKER = "sedhhytjkss-ats.iot.ap-southeast-1.amazonaws.com";
private static final String CLIENT_ID = "smart_pen";
private static final String TOPIC = "$aws/things/smart_pen/shadow/update";

private static final String AWS_ACCESS_KEY = "DRSFGDFKLSLDSP";
private static final String AWS_SECRET_KEY = "/HHJKlkKLDddkdldsksdpsk255s6";

@GetMapping("/")
public void publishMessageWithPaho() {

    try {
        MqttClient client = new MqttClient(BROKER, CLIENT_ID);
        MqttConnectOptions options = new MqttConnectOptions();
        options.setUserName(AWS_ACCESS_KEY);
        options.setPassword(AWS_SECRET_KEY.toCharArray());
        client.connect(options);

        MqttMessage message = new MqttMessage();
        message.setPayload("First message".getBytes());
        message.setQos(0);

        client.publish(TOPIC, message);

        client.disconnect();
    } catch (MqttException e) {
        e.printStackTrace();
    }
}