private void addMap(StringBuilder b,DockerFileKeyword keyword, Map<String,String> map) {
        if (map != null && map.size() > 0) {
            String entries[] = new String[map.size()];
            int i = 0;
            for (Map.Entry<String, String> entry : map.entrySet()) {
                entries[i++] = createKeyValue(entry.getKey(), entry.getValue());
            }
            keyword.addTo(b, entries);
        }
    }
Create a Dockerfile following the format described in the
<a href="http://docs.docker.io/reference/builder/#usage">Docker reference manual</a>

@return the dockerfile create
@throws IllegalArgumentException if no src/dest entries have been added
src/main/java/io/fabric8/maven/docker/assembly/DockerFileBuilder.java