R - The type of the result returned by this query.
public interface Query<R>
You can find all available queries by searching for classes implementing this interface.
Kafka Streams will pass unknown query types straight through into the bytes stores, so callers
can add custom queries by implementing this interface and providing custom stores that handle
See KIP-796 (https://cwiki.apache.org/confluence/x/34xnCw) for more details.