private static String extractValidFromLine(String[] fromLine) {
        String validFrom = fromLine[1];
        for (int i = 1; i < fromLine.length; i++) {
            if (!fromLine[i].startsWith("--")) {
                validFrom = fromLine[i];
                break;
            }
        }
        return validFrom;
    }
Extract the base images from a dockerfile. All lines containing a <code>FROM</code> is
taken.

@param dockerFile file from where to extract the base image
@param interpolator interpolator for replacing properties
@return LinkedList of base images name or empty collection if none is found.
src/main/java/io/fabric8/maven/docker/util/DockerFileUtil.java