private String getArchiveType(ImageConfiguration imageConfig) {
        return imageConfig.getBuildConfiguration().getCompression().getFileSuffix();
    }
Mode how to attach the source artifact:

<ul>
    <li><strong>first</strong> : The first image with build configuration</li>
    <li><strong>all</strong> : All images with build configuration. Each image must have an alias
       configured which is use as part of the classifier.
    </li>
</ul>
src/main/java/io/fabric8/maven/docker/SourceMojo.java