code: public CustomWindowStateType<PortletDescriptor> getOrCreateCustomWindowState()
     {
        List<Node> nodeList = model.get("custom-window-state");
        if (nodeList != null &&  nodeList.size() > 0)
        {
           return new CustomWindowStateTypeImpl<PortletDescriptor>(this, "custom-window-state", model, nodeList.get(0));
        }
        return createCustomWindowState();
     }
docs: If not already created, a new <code>custom-window-state</code> element will be created and returned.
  Otherwise, the first existing <code>custom-window-state</code> element will be returned.
  @return the instance defined for the element <code>custom-window-state</code>