private static String map(RefType refType) {
		String edgeTypeName = fixup(refType.getName());
		refTypeToEdgeTypeMap.put(refType, edgeTypeName);
		return edgeTypeName;
	}
Defines a common set of vertex and edge types {@link GraphType} for program code and data flow
graphs. Each specific type of program graph will use a subclass to specifically identify the
graph type.
Ghidra/Features/Base/src/main/java/ghidra/graph/ProgramGraphType.java