@Test
public void tryToGetInstanceWithEmptyAcknowledgements() {

    assertThatExceptionOfType(IllegalArgumentException.class)
            .isThrownBy(() -> ImmutableAcknowledgements.of(Collections.emptySet(), KNOWN_DITTO_HEADERS))
            .withMessage("The argument 'acknowledgements' must not be empty!")
            .withNoCause();
}