@Override
protected void encode(Encoder encoder, Object value, OutputStream output, Operation op)
throws IOException, ServiceException {
GetPropertyValueType request = (GetPropertyValueType) op.getParameters()[0];
QueryType query = (QueryType) request.getAbstractQueryExpression();
QName typeName = (QName) query.getTypeNames().get(0);
NamespaceInfo ns = gs.getCatalog().getNamespaceByURI(typeName.getNamespaceURI());
encoder.getNamespaces().declarePrefix(ns.getPrefix(), ns.getURI());
encoder.encode(value, WFS.ValueCollection, output);