@Override
	FGVertex getVertex(FGController controller, Map<AddressHasher, FGVertex> vertexMap) {

// 7937:D - when we can't find a grouped vertex after restoring from XML, do we give 
//		             up completely?  Do we just ignore that vertex and keep grouping others?

		//
		// GroupedVertexInfos must be processed first, as they are processed, they will remove
		// edges from the graph that should not be in the final GroupedVertex created here.  Also,
		// we need any edges for the subgroups to exist in the graph so that the group vertex
		// created here will get those edges.
		//
		Set<GroupedVertexInfo> groupInfos = getGroupVertexInfos(vertexInfos);

		Set<FGVertex> vertices = new HashSet<>();
		Set<FGEdge> edges = new HashSet<>();
		createVertexAndEdges(controller, vertexMap, groupInfos, vertices, edges);

		//
		// Now process the remaining non-group infos
		//
		HashSet<VertexInfo> nonGroupInfos = new HashSet<>(vertexInfos);
		nonGroupInfos.removeAll(groupInfos); // what's left is the vertex infos
		createVertexAndEdges(controller, vertexMap, nonGroupInfos, vertices, edges);

		if (vertices.isEmpty()) {
			// this implies the graph structure has changes such that the originally grouped
			// blocks no longer exist
			return null;
		}

		GroupedFunctionGraphVertex vertex =
			new GroupedFunctionGraphVertex(controller, userText, vertices, edges);
		Color defaultBackgroundColor = vertex.getDefaultBackgroundColor();
		if (!defaultBackgroundColor.equals(backgroundColor)) {
			vertex.setBackgroundColor(backgroundColor);
		}

		return vertex;
	}
Locates a vertex for the given info <b>without creating that vertex</b>.  This is in 
contrast to {@link #getVertex(FGController, Map)}, which will create a vertex
(and supporting vertices if it is a group).

@param controller the controller of the current graph
@param vertexMap a mapping of hashed addresses to vertices (creating this upfront is more
       efficient when using it over different {@link GroupedVertexInfo} instances.
@return an existing vertex; null if one does not exist
Ghidra/Features/FunctionGraph/src/main/java/ghidra/app/plugin/core/functiongraph/graph/vertex/GroupedVertexInfo.java