@Override
    public <V1, R> KTable<K, R> outerJoin(final KTable<K, V1> other,
                                          final ValueJoiner<? super V, ? super V1, ? extends R> joiner) {
        return outerJoin(other, joiner, NamedInternal.empty());
    }
@Test
    public void shouldNotAllowNullOtherTableOnOuterJoin() {
        assertThrows(NullPointerException.class, () -> table.outerJoin(null, MockValueJoiner.TOSTRING_JOINER));
    }