public Set<FGEdge> createDummySources() {

		Set<FGEdge> dummyEdges = new HashSet<>();
		Set<FGVertex> entries = getEntryPoints();
		for (FGVertex entry : entries) {
			AbstractFunctionGraphVertex abstractVertex = (AbstractFunctionGraphVertex) entry;
			FGController controller = abstractVertex.getController();
			ListingFunctionGraphVertex newEntry = new DummyListingFGVertex(controller,
				abstractVertex.getAddresses(), RefType.UNCONDITIONAL_JUMP, true);
			newEntry.setVertexType(FGVertexType.ENTRY);
			FGVertex groupVertex = getVertexForAddress(entry.getVertexAddress());
			FGEdgeImpl edge =
				new FGEdgeImpl(newEntry, groupVertex, RefType.UNCONDITIONAL_JUMP, options);
			dummyEdges.add(edge);
		}

		return dummyEdges;
	}
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 entry to a new dummy 
vertex that is a source 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