public static Map<String, String> extractArgs(File dockerfile, Map<String, String> argsFromBuildConfig, FixedStringSearchInterpolator interpolator) throws IOException {
        return extractArgsFromLines(extractLines(dockerfile, "ARG", interpolator), argsFromBuildConfig);
    }
Extract Args from dockerfile. All lines containing ARG is taken.

@param dockerfile Docker File
@param interpolator interpolator for replacement
@return HashMap of arguments or empty collection if none is found
src/main/java/io/fabric8/maven/docker/util/DockerFileUtil.java