private File getAndEnsureOutputDirectory() {
        File outputDir = new File(new File(project.getBuild().getDirectory()), DOCKER_EXTRA_DIR);
        if (!outputDir.exists()) {
            outputDir.mkdirs();
        }
        return outputDir;
    }
Helper method to process an ImageConfiguration.

@param hub ServiceHub
@param aImageConfig ImageConfiguration that would be forwarded to build and tag
@throws DockerAccessException
@throws MojoExecutionException
src/main/java/io/fabric8/maven/docker/BuildMojo.java