private boolean eitherGroupedEndpoint(FGVertex startVertex, FGVertex destinationVertex) {
		return startVertex instanceof GroupedFunctionGraphVertex ||
			destinationVertex instanceof GroupedFunctionGraphVertex;
	}
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