4.3.2 to 4.3.3 Upgrade Guide

HiveMQ Extensions

Multiple HiveMQ extensions must be upgraded to the latest version when used with HiveMQ 4.3.3.

The affected extensions and their new minimum versions are:

Open Source Extensions

Custom Extensions

It can be required to adapt custom HiveMQ extensions.

The needed adaptions are:

  • A dependency on the javax.xml.bind:jaxb-api package must be changed to the jakarta.xml.bind:jakarta.xml.bind-api package version 2.3.3 or higher.

  • A dependency on the com.sun.xml.bind:jaxb-impl package must be updated to version 2.3.3 or higher.

  • A dependency on the javax.activation:javax.activation-api package must be changed to the jakarta.activation:jakarta.activation-api package version 1.2.2 or higher.

  • A dependency on the com.sun.activation:javax.activation must be changed to the com.sun.activation:jakarta.activation package version `1.2.2`or higher.

Usage of ByteBuffer in the Extension SDK

The HiveMQ Extension System provides ByteBuffer objects in multiple input parameters. To improve the isolation between extensions, the ByteBuffers are now consistently read-only. Your extensions cannot rely on write access to the ByteBuffer. For example, it is no longer possible to directly access the array inside the ByteBuffer.

public class MySimpleAuthenticator implements SimpleAuthenticator {

    public void onConnect(SimpleAuthInput input, SimpleAuthOutput output) {


        final ConnectPacket connectPacket = input.getConnectPacket();

        if (connectPacket.getPassword().isPresent()) {

            ByteBuffer readonlyPassword = connectPacket.getPassword().get();

            // If you want to change the password, copy the password to a new modifiable byte array.
            byte[] modifiablePassword = getBytesFromBuffer(password);


    private byte[] getBytesFromBuffer(ByteBuffer byteBuffer) {
        byte[] bytes = new byte[byteBuffer.remaining()];
        return bytes;