public Set<AttributedVertex> convertToOutermostVertices(Set<AttributedVertex> vertices) {
		Set<AttributedVertex> set = new HashSet<>();
		for (AttributedVertex v : vertices) {
			set.add(getOutermostVertex(v));
		}
		return set;
	}
Converts the given set of vertices to a new set where any vertices that are part of a group
are replaced with the outermost group containing it.
 
@param vertices the set of vertices to possibly convert to containing group nodes
@return a converted set of vertices where all vertices part of a group have been replace with
its containing outermost GroupNode.
Ghidra/Features/GraphServices/src/main/java/ghidra/graph/visualization/GhidraGraphCollapser.java