class VizModelPersistenceProvider implements WorkspaceXMLPersistenceProvider {

    @Override
    public void writeXML(XMLStreamWriter writer, Workspace workspace) {<FILL_FUNCTION_BODY>}

    @Override
    public void readXML(XMLStreamReader reader, Workspace workspace) {
        VizModel vizModel = workspace.getLookup().lookup(VizModel.class);
        if (vizModel == null) {
            vizModel = new VizModel(workspace);
            workspace.add(vizModel);
        }
        Lookup.getDefault().lookup(VizController.class)
            .refreshWorkspace();//Necessary to get events from reading xml properties such as background color changed
        try {
            vizModel.readXML(reader, workspace);
        } catch (XMLStreamException ex) {
            throw new RuntimeException(ex);
        }
    }

    @Override
    public String getIdentifier() {
        return "vizmodel";
    }
}

        VizModel model = workspace.getLookup().lookup(VizModel.class);
        if (model != null) {
            try {
                model.writeXML(writer);
            } catch (XMLStreamException ex) {
                throw new RuntimeException(ex);
            }
        }
    
<no_super_class>