@Override
 public SettingSpecifierProviderFactory getProviderFactory(String factoryUID) {
   synchronized (factories) {
     FactoryHelper helper = factories.get(factoryUID);
     if (helper != null) {
       return helper.getFactory();
     }
     return null;
   }
 }
 @Override
 public List<SettingSpecifierProviderFactory> getProviderFactories() {
   List<SettingSpecifierProviderFactory> results;
   synchronized (factories) {
     results = new ArrayList<SettingSpecifierProviderFactory>(factories.size());
     for (FactoryHelper helper : factories.values()) {
       results.add(helper.getFactory());
     }
     return results;
   }
 }