@Override
    public int compare(final Bytes cacheKey, final Windowed<Bytes> storeKey) {
        final Bytes storeKeyBytes = SessionKeySchema.toBinary(storeKey);
        return cacheFunction.compareSegmentedKeys(cacheKey, storeKeyBytes);
    }
Merges two iterators. Assumes each of them is sorted by key
streams/src/main/java/org/apache/kafka/streams/state/internals/MergedSortedCacheSessionStoreIterator.java