@Test
public void filterValueWithEmptyAcknowledgementLabel() {

    final DittoHeaderDefinition headerDefinition = DittoHeaderDefinition.REQUESTED_ACKS;
    final JsonArray allAcknowledgementRequestsJsonArray = JsonArray.newBuilder()
            .add("foo", "", "baz")
            .build();
    final String value = allAcknowledgementRequestsJsonArray.toString();
    final JsonArray externalAcknowledgementRequests = allAcknowledgementRequestsJsonArray.toBuilder()
            .remove(1)
            .build();
    final String expected = externalAcknowledgementRequests.toString();
    final DittoAckRequestsFilter underTest = DittoAckRequestsFilter.getInstance();
    assertThat(underTest.apply(headerDefinition.getKey(), value)).isEqualTo(expected);
}