private Set<FGVertex> generateUngroupedVertices() {
		Set<FGVertex> ungrouped = new HashSet<>();
		for (FGVertex v : getVertices()) {
			accumulateUngroupedVertices(v, ungrouped);
		}
		return 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