@Override
	public synchronized void clearUndo() {
		undoList.clear();
		redoList.clear();
	}
Construct a new ProgramChangeSet.
@param addrMap the address map.
@param numUndos the number of undo change sets to track.
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/database/ProgramDBChangeSet.java