Set<FeatureId> fids = new HashSet();
String fid1 = "station_no.1";// exists
String fid2 = "station_no.500";// doesn't exists
fids.add(ff.featureId(fid1));
fids.add(ff.featureId(fid2));
Id fidFilter = ff.id(fids);
Filter unrolled = (Filter) fidFilter.accept(visitor, null);
assertNotNull(unrolled);
assertTrue(unrolled instanceof OrImpl);
List<Filter> filters = ((OrImpl) unrolled).getChildren();
assertEquals(2, filters.size());
for (Filter f : filters) {