public static Map<String, String> toValueMap(Map<String, FileReference> map) {
        Map<String, String> ret = new LinkedHashMap<>();
        for (Map.Entry<String, FileReference> e : map.entrySet()) {
            ret.put(e.getKey(), e.getValue().value());
        }
        return ret;
    }
An immutable file reference.

@author Tony Vaagenes
config-lib/src/main/java/com/yahoo/config/FileReference.java