@Override
    public V fetch(final K key,
                   final long time) {
        return getValueOrNull(inner.fetch(key, time));
    }
@Test
    public void shouldReturnPlainKeyValuePairsOnSingleKeyFetchInstantParameters() {
        when(mockedWindowTimestampIterator.next())
            .thenReturn(KeyValue.pair(21L, ValueAndTimestamp.make("value1", 22L)))
            .thenReturn(KeyValue.pair(42L, ValueAndTimestamp.make("value2", 23L)));
        when(mockedWindowTimestampStore.fetch("key1", Instant.ofEpochMilli(21L), Instant.ofEpochMilli(42L)))
            .thenReturn(mockedWindowTimestampIterator);

        final WindowStoreIterator<String> iterator =
            readOnlyWindowStoreFacade.fetch("key1", Instant.ofEpochMilli(21L), Instant.ofEpochMilli(42L));

        assertThat(iterator.next(), is(KeyValue.pair(21L, "value1")));
        assertThat(iterator.next(), is(KeyValue.pair(42L, "value2")));
    }