@Test
public void fromDittoHeaders() {

    final DittoHeaders dittoHeaders =
            DittoHeaders.newBuilder().ifMatch(fromCommaSeparatedString("*")).build();
    final Optional<IfMatchPreconditionHeader> ifMatchPreconditionHeader =
            IfMatchPreconditionHeader.fromDittoHeaders(dittoHeaders);
    assertThat(ifMatchPreconditionHeader).isPresent();
    assertThat(ifMatchPreconditionHeader.get().getKey()).isEqualTo("if-match");
    assertThat(ifMatchPreconditionHeader.get().getValue()).isEqualTo("*");
}