public ValueStoreKey nextKey() {
        if (uniqueId == MAX_UNIQUE_ID) {
            throw new RuntimeException(LogUtil.message(
                    "Unable to create the next key as the max ID {} has been reached",
                    MAX_UNIQUE_ID));
        }
        return new ValueStoreKey(valueHashCode, (short) (uniqueId + 1));
    }
@return A new Key instance with the next unique ID. Should be used with some form of
concurrency protection to avoid multiple keys with the same ID.
stroom-pipeline/src/main/java/stroom/pipeline/refdata/store/offheapstore/ValueStoreKey.java