@Override
    public KeyValue<Windowed<Bytes>, byte[]> deserializeStorePair(final KeyValue<Windowed<Bytes>, byte[]> pair) {
        return pair;
    }
Merges two iterators. Assumes each of them is sorted by key
streams/src/main/java/org/apache/kafka/streams/state/internals/MergedSortedCacheSessionStoreIterator.java