@Override
    public byte[] putIfAbsent(final Bytes key,
                              final byte[] valueAndTimestamp) {
        final byte[] previous = wrapped().putIfAbsent(key, valueAndTimestamp);
        if (previous == null) {
            // then it was absent
            log(key, rawValue(valueAndTimestamp), valueAndTimestamp == null ? context.timestamp() : timestamp(valueAndTimestamp));
        }
        return previous;
    }
@Test
    public void shouldReturnNullOnPutIfAbsentWhenNoPreviousValue() {
        assertThat(store.putIfAbsent(hi, rawThere), is(nullValue()));
    }