private String getRefGroup(Reference ref) {
		if (ref.isMemoryReference()) {
			return "Memory";
		}
		else if (ref.isExternalReference()) {
			return "External";
		}
		else if (ref.isStackReference()) {
			return "Stack";
		}
		if (ref.isRegisterReference()) {
			return "Register";
		}
		return "Unknown";
	}
Replace the fallthroughs where possible. 
@param addressSet the address set where fallthroughs should be replaced
@param chosenConflictOption indicator of where to get references from (KEEP_ORIGINAL, KEEP_LATEST, KEEP_MY).
@param monitor task monitor
@throws CancelledException if user cancels.
Ghidra/Features/Base/src/main/java/ghidra/app/merge/listing/ReferenceMerger.java