@Test
public void entriesSizeIsGreaterThanZeroIfHeadersAreNotEmpty() {

    final ImmutableDittoHeaders underTest = ImmutableDittoHeaders.of(
            Maps.newHashMap(DittoHeaderDefinition.CORRELATION_ID.getKey(), KNOWN_CORRELATION_ID));
    assertThat(underTest.isEntriesSizeGreaterThan(0)).isTrue();
}