@Test
public void mapFromMessageWithTextPayload() {

    final DittoHeaders dittoHeaders = DittoHeaders.newBuilder().randomCorrelationId().build();
    final Message<Object> message = messageBuilder("text/plain")
            .payload("hello world")
            .build();
    final Signal<?> sendThingMessage = SendThingMessage.of(THING_ID, message, dittoHeaders);
    final List<ExternalMessage> result = underTest.map(ADAPTER.toAdaptable(sendThingMessage));
    assertThat(result).hasSize(1);
    assertThat(result.get(0).getBytePayload()).isEmpty();
    assertThat(result.get(0).getTextPayload()).contains("hello world");
    assertThat(result.get(0).getHeaders()).containsExactlyEntriesOf(message.getHeaders());
}