@Test
public void tryToGetInstanceWithNullDittoHeaders() {

    assertThatNullPointerException()
            .isThrownBy(() -> ImmutableAcknowledgement.of(KNOWN_ACK_LABEL, KNOWN_ENTITY_ID, KNOWN_STATUS_CODE, null,
                    null))
            .withMessage("The dittoHeaders must not be null!")
            .withNoCause();
}