@Test
public void mapFromMessageWithDittoProtocolContentType() {

    final DittoHeaders dittoHeaders = DittoHeaders.newBuilder()
            .randomCorrelationId()
            .contentType("application/vnd.eclipse.ditto+json")
            .build();
    final Message<Object> messageWithoutPayload = messageBuilder(null).payload("hello world").build();
    final Signal<?> sendThingMessage = SendThingMessage.of(THING_ID, messageWithoutPayload, dittoHeaders);
    final Adaptable adaptable = ADAPTER.toAdaptable(sendThingMessage);
    final List<ExternalMessage> result = underTest.map(adaptable);
    final List<ExternalMessage> expectedResult = new DittoMessageMapper().map(adaptable);
    assertThat(result).isEqualTo(expectedResult);
}