private IPortletWindowId getPortletWindowId(HttpServletRequest request, String layoutNodeId) {
if (layoutNodeId == null) {
return null;
}
final LayoutNodeType layoutNodeType = this.getLayoutNodeType(request, layoutNodeId);
if (layoutNodeType == null) {
throw new IllegalArgumentException("No layout node exists for id: " + layoutNodeId);
}
if (layoutNodeType != LayoutNodeType.PORTLET) {