Set successors = new HashSet();
Iterator outports = actor.outputPortList().iterator();
while (outports.hasNext()) {
IOPort outPort = (IOPort) outports.next();
Iterator sinkPorts = outPort.sinkPortList().iterator();
while (sinkPorts.hasNext()) {
IOPort sinkPort = (IOPort) sinkPorts.next();
if (sinkPort.isOutput()) {