EDIT

     * Convenience method returning only the list of states. Leaving out modifiers and modifying text.

        List<State> result = new ArrayList<>();

            if (state != null){

                result.add(state);

            }

        if(aggregatedCategoricalData == null){

            if (!aggregatedCategoricalData.getStatesOnly().isEmpty()){

                aggregatedCategoricalData.getStateData().stream().filter(sd->sd.getCount()==null).forEach(sd->sd.incrementCount());

                resultHolder.categoricalMap.put(aggregatedCategoricalData.getFeature(), aggregatedCategoricalData);

            }

        //create empty categorical data

        //test aggregation with categorical data without states (empty categorical data)

        verifyStatusOk(result);

        //if no state at all exists in description even the description is not created (this was different before but changed with xxx)

        verifyNumberTaxonDescriptions(taxLapsanaCommunisAlpina, 0);

        //add data for another feature

        specDescAlpina1 = (SpecimenDescription)descriptionService.find(specDescAlpina1.getUuid());

        addCategoricalData(specDescAlpina1, uuidFeatureLeafPA, State.uuidPresent);

        commitAndStartNewTransaction();

        result = engine.invoke(config, repository);

        verifyStatusOk(result);

        taxLapsanaCommunisAlpina = (Taxon)taxonService.find(T_LAPSANA_COMMUNIS_ALPINA_UUID);

        verifyNumberDescriptionElements(aggrDescLapsanaCommunisAlpina, uuidFeatureLeafColor, 0);

//        List<StateData> sdAlpinaLeafColor = verifyCategoricalData(uuidFeatureLeafColor, 0, aggrDescLapsanaCommunisAlpina, false);

//        verifyState(sdAlpinaLeafColor, uuidLeafColorBlue, 0);

//        verifyState(sdAlpinaLeafColor, uuidLeafColorYellow, 0);

        //test duplicates

        specDescAlpina1 = (SpecimenDescription)descriptionService.find(specDescAlpina1.getUuid());

        addCategoricalData(specDescAlpina1, uuidFeatureLeafColor, uuidLeafColorBlue);

        addCategoricalData(specDescAlpina1, uuidFeatureLeafColor, uuidLeafColorBlue);

        commitAndStartNewTransaction();

        result = engine.invoke(config, repository);

        verifyStatusOk(result);

        taxLapsanaCommunisAlpina = (Taxon)taxonService.find(T_LAPSANA_COMMUNIS_ALPINA_UUID);

        aggrDescLapsanaCommunisAlpina = verifyTaxonDescriptions(taxLapsanaCommunisAlpina, 2);  //for leafPA and for color

        verifyState(sdAlpinaLeafColor, uuidLeafColorBlue, 2);

    private TaxonDescription verifyTaxonDescriptions(Taxon taxon, int elementCount){

        List<TaxonDescription> aggrNonCloneTaxonDescriptions = taxon.getDescriptions().stream()

        Assert.assertEquals(1, aggrNonCloneTaxonDescriptions.size());

        TaxonDescription aggrDesc = aggrNonCloneTaxonDescriptions.iterator().next();

        Assert.assertEquals(elementCount, elements.size());

    private void verifyNumberTaxonDescriptions(Taxon taxon, long descriptionCount){

        long n = taxon.getDescriptions().stream()

            .filter(desc->desc.getTypes().contains(DescriptionType.AGGREGATED_STRUC_DESC))

            .filter(desc->!desc.getTypes().contains(DescriptionType.CLONE_FOR_SOURCE)).count();

        Assert.assertEquals(descriptionCount, n);

    }

    private void verifyNumberDescriptionElements(DescriptionBase<?> description, UUID featureUuid, long elementCount){

        long n = description.getElements().stream()

                .filter(element->element.getFeature().getUuid().equals(featureUuid))

                .map(catData->CdmBase.deproxy(catData, CategoricalData.class))

                .count();

        Assert.assertEquals(elementCount, n);

    }