    @Test
    public void simpleCopyToSameExistingAnnoTest()
        throws Exception
    {

        CAS jcas = createJCas().getCas();
        Type type = jcas.getTypeSystem().getType(POS.class.getTypeName());
        AnnotationFS clickedFs = createPOSAnno(jcas, "NN", 0, 0);

        CAS mergeCas = createJCas().getCas();
        AnnotationFS existingFs = mergeCas.createAnnotation(type, 0, 0);
        Feature posValue = type.getFeatureByBaseName("PosValue");
        existingFs.setStringValue(posValue, "NN");
        mergeCas.addFsToIndexes(existingFs);

        Assertions.assertThatExceptionOfType(AnnotationException.class)
                .isThrownBy(() -> sut.mergeSpanAnnotation(null, null, posLayer, mergeCas, 
                        clickedFs, false))
                .withMessageContaining("annotation already exists");
    }