@Override
    public void to(final String topic) {
        to(topic, Produced.with(keySerde, valueSerde, null));
    }
@Test
    public void shouldNotAllowNullProducedOnToWithTopicChooser() {
        final NullPointerException exception = assertThrows(
            NullPointerException.class,
            () -> testStream.to((k, v, ctx) -> "topic", null));
        assertThat(exception.getMessage(), equalTo("produced can't be null"));
    }