public static RankFeatureNormalizer rrank(Reference original, Reference inputRef, double k) {
            long h = hash(original.toString());
            String name = "normalize@" + h + "@rrank";
            return new RankFeatureNormalizer(original, name, inputRef.toString(), "RRANK", k);
        }
Returns the path type, if valuePath is set.
config-model/src/main/java/com/yahoo/schema/RankProfile.java