private void accumulateUngroupedVertices(FGVertex v, Set<FGVertex> ungrouped) {
		if (!(v instanceof GroupedFunctionGraphVertex)) {
			ungrouped.add(v);
			return;
		}

		GroupedFunctionGraphVertex gv = (GroupedFunctionGraphVertex) v;
		Set<FGVertex> grouped = gv.getVertices();
		for (FGVertex child : grouped) {
			accumulateUngroupedVertices(child, ungrouped);
		}
	}
This method returns all vertices known by this class.  This differs from the vertices
returned from {@link Graph} in that those may be a smaller subset of the collection returned
here.  Due to graph manipulation after creation time (e.g., vertex grouping), the
vertices known by the {@link Graph} may not include all vertices created at the same time
as the graph and any others created by graph mutating operations <b>that are not the
result of a grouping operation</b>.

@return all vertices known by this class, visible or not.
Ghidra/Features/FunctionGraph/src/main/java/ghidra/app/plugin/core/functiongraph/graph/FunctionGraph.java