[Geotools-gt2-users] How do i sort features returned from featureCollectuion?

[LSA <ls...@ng...>]

I am using geotools 2.6.3.

I try do it like this:
FeatureCollection features = getFeatures();
org.opengis.feature.type.Name name = 
features.getSchema().getDescriptor("MyAttr").getName();
features = features.sort(new SortByImpl(filterFactory.property(name), 
SortOrder.ASCENDING));

However, it fails with NPE (because index==null) at getFeatureMember ( 
int position = index.indexOf( id );), when I call *features*.features():

public SimpleFeature getFeatureMember( String id ) throws 
NoSuchElementException {
         int position = index.indexOf( id );
         if( position == -1){
             throw new NoSuchElementException(id);
         }
         if( collection instanceof RandomFeatureAccess ){
             RandomFeatureAccess random = (RandomFeatureAccess) collection;
             random.getFeatureMember( id );
         }
         return (SimpleFeature) get( position );
     }

Any ideas?

Thanks in advance,
Sergey