private static void addActivity(
      Set<TransitionTarget> visited,
      List<TransitionTarget> targets,
      IActivity target,
      TransitionOptions options,
      boolean forward,
      Stack<TransitionStep> steps) {
    TransitionTarget candidate =
        TransitionTargetFactory.createTransitionTarget(target, steps, forward);
    if (!visited.add(candidate)) {
      // target already visited, stop processing
      return;
    }
    if (target.getBooleanAttribute(PredefinedConstants.ACTIVITY_IS_RELOCATE_TARGET_ATT)) {
      // found a relocation target, check filters
      String processIdPattern = options.getProcessIdPattern();
      if (processIdPattern == null
          || target.getProcessDefinition().getId().matches(processIdPattern)) {
        String activityIdPattern = options.getActivityIdPattern();
        if (activityIdPattern == null || target.getId().matches(activityIdPattern)) {
          targets.add(candidate);
        }
      }
    }

    if (options.isTransitionIntoSubprocessesAllowed()
        && target.getImplementationType() == ImplementationType.SubProcess
        && target.getSubProcessMode() != SubProcessModeKey.ASYNC_SEPARATE) {
      IProcessDefinition process = target.getImplementationProcessDefinition();
      if (process != null) {
        steps.push(TransitionTargetFactory.createTransitionStep(target));
        addActivities(visited, targets, process, options, forward, steps);
        steps.pop();
      }
    }

    addActivities(visited, targets, target, options, forward, steps);
  }
 private static void addActivities(
     Set<TransitionTarget> visited,
     List<TransitionTarget> targets,
     IActivityInstance ai,
     TransitionOptions options,
     boolean forward,
     Stack<TransitionStep> steps) {
   if (ai != null) {
     steps.push(TransitionTargetFactory.createTransitionStep(ai));
     // add activities from current process definition
     addActivities(visited, targets, ai.getActivity(), options, forward, steps);
     // step up into the calling process - starting activity cannot be a relocation target
     if (options.isTransitionOutOfSubprocessesAllowed()) {
       addActivities(
           visited,
           targets,
           ai.getProcessInstance().getStartingActivityInstance(),
           options,
           forward,
           steps);
     }
     steps.pop();
   }
 }