Program: 90800
Project: 90800
Buggy source:
public FunctionElementArgument<?> evaluate(){
  if (expression == null || expression.isEmpty()) {
    throw new RuntimeException("String_Node_Str");
  }
  LinkedList<ExpressionElement> stack=new LinkedList<ExpressionElement>();
  for (  ExpressionElement element : expression) {
    if (element instanceof FunctionElementArgument) {
      stack.push(element);
    }
 else     if (element instanceof FunctionElement) {
      FunctionElement function=(FunctionElement)element;
      int numArgs=function.getNumberOfParameters();
      FunctionElementArgument<?> args[]=new FunctionElementArgument<?>[numArgs];
      for (int i=0; i < numArgs; i++) {
        ExpressionElement arg=stack.pop();
        if (arg instanceof FunctionElementArgument) {
          int argIndex=numArgs - 1 - i;
          args[argIndex]=(FunctionElementArgument<?>)arg;
          if (arg instanceof VariableArgument) {
            VariableArgument variable=(VariableArgument)arg;
            Variable boundVariable=boundVariables.get(variable.getName());
            args[argIndex]=replaceVariable(boundVariable.getValue());
          }
        }
 else {
          throw new IllegalArgumentException("String_Node_Str" + arg.getClass().getName());
        }
      }
      FunctionElementArgument<?> result=function.execute(args);
      stack.push(result);
    }
 else {
      throw new IllegalArgumentException("String_Node_Str" + element.getClass().getName());
    }
  }
  if (stack.size() != 1) {
    throw new IllegalArgumentException("String_Node_Str" + stack.size());
  }
  ExpressionElement element=stack.pop();
  if (element instanceof FunctionElementArgument) {
    return (FunctionElementArgument<?>)element;
  }
 else {
    throw new IllegalArgumentException("String_Node_Str" + element.getClass().getName());
  }
}

Fixed version (ground truth):
public FunctionElementArgument<?> evaluate(){
  if (expression == null || expression.isEmpty()) {
    throw new RuntimeException("String_Node_Str");
  }
  LinkedList<ExpressionElement> stack=new LinkedList<ExpressionElement>();
  for (  ExpressionElement element : expression) {
    if (element instanceof FunctionElementArgument) {
      stack.push(element);
    }
 else     if (element instanceof FunctionElement) {
      FunctionElement function=(FunctionElement)element;
      int numArgs=function.getNumberOfParameters();
      FunctionElementArgument<?> args[]=new FunctionElementArgument<?>[numArgs];
      for (int i=0; i < numArgs; i++) {
        ExpressionElement arg=stack.pop();
        if (arg instanceof FunctionElementArgument) {
          int argIndex=numArgs - 1 - i;
          args[argIndex]=(FunctionElementArgument<?>)arg;
          if (arg instanceof VariableArgument) {
            VariableArgument variable=(VariableArgument)arg;
            Variable boundVariable=boundVariables.get(variable.getName());
            args[argIndex]=replaceVariable(boundVariable.getValue());
          }
        }
 else {
          throw new IllegalArgumentException("String_Node_Str" + arg.getClass().getName());
        }
      }
      FunctionElementArgument<?> result=function.execute(args);
      if (logger.isLoggable(Level.INFO)) {
        String message="String_Node_Str" + result.getValue() + "String_Node_Str"+ result.getType()+ "String_Node_Str"+ function.getName()+ "String_Node_Str";
        for (int i=0; i < numArgs; i++) {
          message+=args[i].getValue() + "String_Node_Str" + args[i].getType()+ "String_Node_Str";
          if (i + 1 < numArgs) {
            message+="String_Node_Str";
          }
        }
        message+="String_Node_Str";
        logger.info(message);
      }
      stack.push(result);
    }
 else {
      throw new IllegalArgumentException("String_Node_Str" + element.getClass().getName());
    }
  }
  if (stack.size() != 1) {
    throw new IllegalArgumentException("String_Node_Str" + stack.size());
  }
  ExpressionElement element=stack.pop();
  if (element instanceof FunctionElementArgument) {
    return (FunctionElementArgument<?>)element;
  }
 else {
    throw new IllegalArgumentException("String_Node_Str" + element.getClass().getName());
  }
}