private void initDockerFileFile(Logger log) {
        // can't have dockerFile/dockerFileDir and dockerArchive
        if ((dockerFile != null || dockerFileDir != null) && dockerArchive != null) {
            throw new IllegalArgumentException("Both <dockerFile> (<dockerFileDir>) and <dockerArchive> are set. " +
                                               "Only one of them can be specified.");
        }
        dockerFileFile = findDockerFileFile(log);

        if (dockerArchive != null) {
            dockerArchiveFile = new File(dockerArchive);
        }
    }
Use {@link #getAllAssemblyConfigurations()} unless you specifically want the configuration defined only by <code>assemblies</code>.
src/main/java/io/fabric8/maven/docker/config/BuildImageConfiguration.java