@Override
	public GDirectedGraph<FGVertex, FGEdge> emptyCopy() {
		return new FunctionGraph(function, settings);
	}
A method to create dummy edges (with dummy vertices).  This is used to add entry and 
exit vertices as needed when a user grouping operation has consumed the entries or exits.
The returned edge will connect the current vertex containing the exit to a new dummy 
vertex that is a sink for the graph.   Calling this method does not mutate this graph.

@return the edge
Ghidra/Features/FunctionGraph/src/main/java/ghidra/app/plugin/core/functiongraph/graph/FunctionGraph.java