@Override
    public <V1, R> KTable<K, R> join(final KTable<K, V1> other,
                                     final ValueJoiner<? super V, ? super V1, ? extends R> joiner) {
        return doJoin(other, joiner, NamedInternal.empty(), null, false, false);
    }
@Test
    public void shouldAllowNullStoreInJoin() {
        table.join(table, MockValueJoiner.TOSTRING_JOINER);
    }