System.out.println("sender: "+sender+" receiver: "+receiver);
    public static boolean isMessageDirectionDownstream(SIRFilter sender,						       SIRFilter receiver) {	Vector v = new Vector();	v.add(sender);	v.add(receiver);	Boolean b = (Boolean)messageDirectionDownstream.get(v);		System.out.println("sender: "+sender+" receiver: "+receiver);        assert b != null:            "Information about message direction from " + sender + " to " +            receiver + " requested when no such data has been gathered";	return b.booleanValue();    }