@Override
	public synchronized void undo() {
		MyChangeDiff diff = undoList.removeLast();
		changedDataTypeIds.removeAll(diff.changedDts);
		changedCategoryIds.removeAll(diff.changedCats);
		changedSourceArchiveIds.removeAll(diff.changedArchives);
		addedDataTypeIds.removeAll(diff.addedDts);
		addedCategoryIds.removeAll(diff.addedCats);
		addedSourceArchiveIds.removeAll(diff.addedArchives);
		redoList.addLast(diff);
	}
Construct a new DataTypeArchiveChangeSet.
@param addrMap the address map.
@param numUndos the number of undo change sets to track.
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/database/DataTypeArchiveDBChangeSet.java