public Collection<URI> getSupportedFacets(URI needUri) throws NoSuchNeedException {
   List<URI> ret = new LinkedList<URI>();
   Need need = DataAccessUtils.loadNeed(needRepository, needUri);
   Model content = rdfStorageService.loadContent(need);
   if (content == null) return ret;
   Resource baseRes = content.getResource(content.getNsPrefixURI(""));
   StmtIterator stmtIterator = baseRes.listProperties(WON.HAS_FACET);
   while (stmtIterator.hasNext()) {
     RDFNode object = stmtIterator.nextStatement().getObject();
     if (object.isURIResource()) {
       ret.add(URI.create(object.toString()));
     }
   }
   return ret;
 }