public void setRootVertex(FGVertex rootVertex) {
		if (this.rootVertex != null) {
			this.rootVertex = rootVertex;
			return;
		}

		this.rootVertex = rootVertex;

		//
		// Unusual Code Alert!: we are putting into the settings an object that will pull the
		//                      group state of this graph at the time of saving.  This allows
		//                      other clients to clear the settings object, which will also
		//                      clear this lazy loading object, thus preventing saving.  This
		//                      differs a bit from the normal settings mechanism, which is based
		//                      upon either 1) updating the settings object as the data changes, or
		//                      2) pulling the data to save on command.
		//
		settings.putGroupedVertexSettings(this, new LazyGraphGroupSaveableXML(this));
		settings.putRegroupSettings(this, new LazyGraphRegroupSaveableXML(this));
	}
Any time a vertex is grouped we want to make sure that any previous group affiliations
are removed.

@param groupVertices the new grouping of vertices
Ghidra/Features/FunctionGraph/src/main/java/ghidra/app/plugin/core/functiongraph/graph/FunctionGraph.java