Grouped strokes reads from UBZ fine. it is grouped after reading now.

src/adaptors/UBSvgSubsetAdaptor.cpp

@@ -1194,6 +1194,7 @@ bool UBSvgSubsetAdaptor::UBSvgSubsetWriter::persistScene(int pageIndex)
             UBGraphicsStrokesGroup* strokesGroupItem = qgraphicsitem_cast<UBGraphicsStrokesGroup*>(item);
             if(strokesGroupItem && strokesGroupItem->isVisible()){
             	mXmlWriter.writeStartElement("g");
+                mXmlWriter.writeAttribute(UBSettings::uniboardDocumentNamespaceUri, "uuid", UBStringUtils::toCanonicalUuid(strokesGroupItem->uuid()));
             	QMatrix matrix = item->sceneMatrix();
 				if (!matrix.isIdentity()){
 					mXmlWriter.writeAttribute("transform", toSvgTransform(matrix));