@Test
public void mapToNonMessageCommandWithDittoProtocolContentType() {

    final Signal<?> signal = ThingDeleted.of(ThingId.of("thing:id"), 25L, DittoHeaders.empty());
    final Adaptable adaptable = ADAPTER.toAdaptable(signal);
    final ExternalMessage externalMessage = new DittoMessageMapper().map(adaptable).get(0)
            .withHeader("content-type", "application/vnd.eclipse.ditto+json");
    final List<Adaptable> mapped = underTest.map(externalMessage);
    assertThat(mapped).hasSize(1);
    assertThat(mapped.get(0)).isEqualTo(adaptable);
}