@Override
    public KeyValueIterator<Windowed<K>, V> backwardFetch(final K key) {
        Objects.requireNonNull(key, "key cannot be null");
        return new MeteredWindowedKeyValueIterator<>(
            wrapped().backwardFetch(keyBytes(key)),
            fetchSensor,
            iteratorDurationSensor,
            streamsMetrics,
            serdes::keyFrom,
            serdes::valueFrom,
            time,
            numOpenIterators,
            openIterators
        );
    }
@Test
    public void shouldThrowNullPointerOnBackwardFetchIfFromIsNull() {
        setUpWithoutContext();
        assertThrows(NullPointerException.class, () -> store.backwardFetch(null, "to"));
    }