private boolean currentGraphContainsReferenceChangedEvent(DomainObjectChangedEvent ev) {
		FGData functionGraphData = controller.getFunctionGraphData();
		FunctionGraph graph = functionGraphData.getFunctionGraph();

		for (DomainObjectChangeRecord record : ev) {
			EventType eventType = record.getEventType();
			if (eventType == ProgramEvent.REFERENCE_ADDED) {
				Reference reference = (Reference) record.getNewValue();
				Address toAddress = reference.getToAddress();
				if (graph.getVertexForAddress(toAddress) != null) {
					return true;
				}
			}
			else if (eventType == ProgramEvent.REFERENCE_REMOVED) {
				Reference reference = (Reference) record.getOldValue();
				Address toAddress = reference.getToAddress();
				if (graph.getVertexForAddress(toAddress) != null) {
					return true;
				}
			}
		}
		return false;
	}
Returns true when something destructive has happened to the data upon which the graph has
created, like a memory block move.
Ghidra/Features/FunctionGraph/src/main/java/ghidra/app/plugin/core/functiongraph/FGProvider.java