public static Set<AttributedVertex> flatten(Collection<AttributedVertex> vertices) {
		Set<AttributedVertex> set = new HashSet<>();
		for (AttributedVertex vertex : vertices) {
			if (vertex instanceof GroupVertex) {
				set.addAll(((GroupVertex) vertex).getContainedVertices());
			}
			else {
				set.add(vertex);
			}
		}
		return set;
	}
fire an event to notify the selected vertices changed
@param selected the list of selected vertices
Ghidra/Features/GraphServices/src/main/java/ghidra/graph/visualization/DefaultGraphDisplay.java