private void warnOnce() {
            if (shouldWarn) {
                deployLogger.log(Level.WARNING, "Using attribute(" + attr +") " + collType + " in ranking expression will always evaluate to 0.0");
                shouldWarn = false;
            }
        }
Creates a context containing the type information of all constants, attributes and query profiles
referable from this rank profile.
config-model/src/main/java/com/yahoo/schema/RankProfile.java