@Override
    public synchronized KeyValueIterator<K, ValueAndTimestamp<V>> range(final K from,
        final K to) {
        return new DelegatingPeekingKeyValueIterator<>(
            name,
            new GenericInMemoryKeyValueIterator<>(this.map.subMap(from, true, to, true).entrySet().iterator()));
    }
This class is a generic version of the in-memory key-value store that is useful for testing when you
 need a basic KeyValueStore for arbitrary types and don't have/want to write a serde
streams/src/test/java/org/apache/kafka/test/GenericInMemoryTimestampedKeyValueStore.java