@Test
public void scanHandledMessageTypes_sagaIsAbstract_returnsEmpty() throws ExecutionException {

    // given
    when(typeScanner.scanForSagas()).thenReturn(Collections.singleton(AbstractHandler.class));
    // when
    Map<Class<? extends Saga>, SagaHandlersMap> classSagaHandlersMapMap = sut.scanHandledMessageTypes();
    // then
    assertThat("Expected map to be empty.", classSagaHandlersMapMap.isEmpty(), is(true));
}