public Set<AttributedVertex> getContainedVertices() {
		return Collections.unmodifiableSet(children);
	}
Returns the set of flattened nodes contained in this node.  In other words, any group nodes
that were given to this group node would have been swapped for the nodes that the groupd node
contained.

@return the set of flattened graph vertices represented by this group node.
Ghidra/Features/GraphServices/src/main/java/ghidra/graph/visualization/GroupVertex.java