protected void fireVerticesRemoved(Collection<V> removed) {
		if (removed.isEmpty()) {
			return;
		}
		changeListeners.forEach(l -> l.verticesRemoved(removed));
	}
Called after one or more vertices have been removed.  The callback will happen after
all removals have taken place.  This is an extension point for subclasses.

@param removed the removed vertices
Ghidra/Framework/Graph/src/main/java/ghidra/graph/graphs/DefaultVisualGraph.java