private void convertGroupedEdge(FGEdge edge, Set<FGEdge> updatedEdges) {
		FGVertex startVertex = edge.getStart();
		FGVertex destinationVertex = edge.getEnd();
		if (!eitherGroupedEndpoint(startVertex, destinationVertex)) {
			updatedEdges.add(edge); // plain old edge
			return;
		}

		// 
		// When both endpoints are groups, we want to get all edges in common for later restoring,
		// as we don't know which edges either group refers to if the group goes away
		//
		if (bothGroupedEndpoints(startVertex, destinationVertex)) {
			Set<FGEdge> intersectingConvertedEdges =
				getIntersectingEdges((GroupedFunctionGraphVertex) startVertex,
					(GroupedFunctionGraphVertex) destinationVertex);
			updatedEdges.addAll(intersectingConvertedEdges);
			return;
		}

		//
		// O.K., one of the endpoints is grouped.  Find out which one and get all edges that
		// have the same start/destination for later restoring,
		// as we don't know which edges the group refers to if the group goes away
		//
		if (startVertex instanceof GroupedFunctionGraphVertex) {
			Set<FGEdge> convertedDestinationEdges =
				((GroupedFunctionGraphVertex) startVertex).getAllEdgesWithDestination(
					destinationVertex);
			updatedEdges.addAll(convertedDestinationEdges);
		}
		else {
			Set<FGEdge> convertedStartEdges =
				((GroupedFunctionGraphVertex) destinationVertex).getAllEdgesWithStart(startVertex);
			updatedEdges.addAll(convertedStartEdges);
		}
	}
Seriously complicated algorithm (conceptually) to ensure that we never store in our 
collection of ungrouped edges (which we may sometime have to re-install) any group vertex, 
as when we go to restore the edges, we do not know how to do so if the group is no 
longer there (like as a result of an ungroup operation).
  
@param edge the edge to resolve/convert from using group vertices as endpoints to using
       real vertices as endpoints
@param updatedEdges all edges that we must record as a result of ungrouping the given edge
Ghidra/Features/FunctionGraph/src/main/java/ghidra/app/plugin/core/functiongraph/graph/vertex/GroupedFunctionGraphVertex.java