@Override
    public KStream<K, V> repartition() {
        return doRepartition(Repartitioned.as(null));
    }
@Test
    public void shouldNotAllowNullRepartitionedOnRepartition() {
        final NullPointerException exception = assertThrows(
            NullPointerException.class,
            () -> testStream.repartition(null));
        assertThat(exception.getMessage(), equalTo("repartitioned can't be null"));
    }