@Override
    public <VO, VR> KStream<K, VR> outerJoin(final KStream<K, VO> otherStream,
                                             final ValueJoiner<? super V, ? super VO, ? extends VR> joiner,
                                             final JoinWindows windows) {
        return outerJoin(otherStream, toValueJoinerWithKey(joiner), windows);
    }
@SuppressWarnings("deprecation")
    @Test
    public void shouldNotAllowNullOtherStreamOnOuterJoinWithStreamJoined() {
        final NullPointerException exception = assertThrows(
            NullPointerException.class,
            () -> testStream.outerJoin(
                null,
                MockValueJoiner.TOSTRING_JOINER,
                JoinWindows.of(ofMillis(10)),
                StreamJoined.as("name")));
        assertThat(exception.getMessage(), equalTo("otherStream can't be null"));
    }