public String doTransform(String tag, Date now) {
                    if (tag.endsWith("-SNAPSHOT")) {
                        return "snapshot-" + new SimpleDateFormat(TIMESTAMP_FORMAT).format(now);
                    }
                    return tag;
                }
Property to lookup for image name which overwrites the calculated default, which is calculated
on the project version and depends whether it is a snapshot project or not.
Used with format modifier %v
src/main/java/io/fabric8/maven/docker/util/ImageNameFormatter.java