Program: 76500
Project: 76500
Buggy source:
/** 
 * Construct a DEProcessor actor with the specified parameters.
 * @param container The composite actor that this actor belongs too.
 * @param name The name of this actor.
 * @param minimumServiceTime The minimum service time.
 * @param interruptServiceTime The interrupt service time.
 * @param lambda The mean interarrival time of the interrupt.adder.
 * @exception IllegalActionException If the entity cannot be containedby the proposed container.
 * @exception NameDuplicationException If the container already has anactor with this name.
 */
public DEProcessor(TypedCompositeActor container,String name,double minimumServiceTime,double interruptServiceTime,double lambda) throws NameDuplicationException, IllegalActionException {
  super(container,name);
  _minimumServiceTime=new Parameter(this,"String_Node_Str",new DoubleToken(minimumServiceTime));
  _interruptServiceTime=new Parameter(this,"String_Node_Str",new DoubleToken(interruptServiceTime));
  _lambda=new Parameter(this,"String_Node_Str",new DoubleToken(lambda));
  output=new TypedIOPort(this,"String_Node_Str",false,true);
  input=new TypedIOPort(this,"String_Node_Str",true,false);
  DECQDirector localDir=new DECQDirector(name + "String_Node_Str");
  this.setDirector(localDir);
  DEInterruptibleServer iServer=new DEInterruptibleServer(this,"String_Node_Str");
  DEPoisson poisson=new DEPoisson(this,"String_Node_Str");
  this.connect(input,iServer.input);
  this.connect(poisson.output,iServer.interrupt);
  this.connect(iServer.output,output);
  Parameter iServerMST=(Parameter)iServer.getAttribute("String_Node_Str");
  Parameter iServerIST=(Parameter)iServer.getAttribute("String_Node_Str");
  Parameter poissonLambda=(Parameter)poisson.getAttribute("String_Node_Str");
  iServerMST.setExpression(_minimumServiceTime.getName());
  _minimumServiceTime.addParameterListener(iServerMST);
  iServerMST.evaluate();
  iServerIST.setExpression(_interruptServiceTime.getName());
  _interruptServiceTime.addParameterListener(iServerIST);
  iServerIST.evaluate();
  poissonLambda.setExpression(_lambda.getName());
  _lambda.addParameterListener(poissonLambda);
  poissonLambda.evaluate();
}

Fixed version (ground truth):
/** 
 * Construct a DEProcessor actor with the specified parameters.
 * @param container The composite actor that this actor belongs too.
 * @param name The name of this actor.
 * @param minimumServiceTime The minimum service time.
 * @param interruptServiceTime The interrupt service time.
 * @param lambda The mean interarrival time of the interrupt.adder.
 * @exception IllegalActionException If the entity cannot be containedby the proposed container.
 * @exception NameDuplicationException If the container already has anactor with this name.
 */
public DEProcessor(TypedCompositeActor container,String name,double minimumServiceTime,double interruptServiceTime,double lambda) throws NameDuplicationException, IllegalActionException {
  super(container,name);
  _minimumServiceTime=new Parameter(this,"String_Node_Str",new DoubleToken(minimumServiceTime));
  _interruptServiceTime=new Parameter(this,"String_Node_Str",new DoubleToken(interruptServiceTime));
  _lambda=new Parameter(this,"String_Node_Str",new DoubleToken(lambda));
  output=new TypedIOPort(this,"String_Node_Str",false,true);
  input=new TypedIOPort(this,"String_Node_Str",true,false);
  DECQDirector localDir=new DECQDirector(name + "String_Node_Str");
  this.setDirector(localDir);
  DEInterruptibleServer iServer=new DEInterruptibleServer(this,"String_Node_Str");
  DEPoisson poisson=new DEPoisson(this,"String_Node_Str");
  this.connect(input,iServer.input);
  this.connect(poisson.output,iServer.interrupt);
  this.connect(iServer.output,output);
  Parameter iServerMST=(Parameter)iServer.getAttribute("String_Node_Str");
  Parameter iServerIST=(Parameter)iServer.getAttribute("String_Node_Str");
  Parameter poissonLambda=(Parameter)poisson.getAttribute("String_Node_Str");
  if (iServerMST == null) {
    System.out.println("String_Node_Str");
  }
  iServerMST.setExpression(_minimumServiceTime.getName());
  iServerMST.evaluate();
  iServerIST.setExpression(_interruptServiceTime.getName());
  iServerIST.evaluate();
  poissonLambda.setExpression(_lambda.getName());
  poissonLambda.evaluate();
}