default KeyValueIterator<Windowed<K>, AGG> backwardFetch(final K key) {
        throw new UnsupportedOperationException(
            "This API is not supported by this implementation of ReadOnlySessionStore.");
    }
Retrieve all aggregated sessions for the provided key. This iterator must be closed after
use.
<p>
For each key, the iterator guarantees ordering of sessions, starting from the newest/latest
available session to the oldest/earliest session.

@param key record key to find aggregated session values for
@return backward KeyValueIterator containing all sessions for the provided key, from newest
to oldest session.
@throws NullPointerException If null is used for key.
streams/src/main/java/org/apache/kafka/streams/state/ReadOnlySessionStore.java