if (tasks[i] == null) throw new RuntimeException ("Prerequisite not found<br>\nPrerequiste " + ids.get(i) + " does not exist for task " + task.getKey()); }
  public Task[] prerequisites (Task task, SchedulingData sd) {    if (prerequisites == null)      return new Task[0];    data.put ("task", task);    ArrayList ids = (ArrayList) prerequisites.getResult (data);    data.remove ("task");    reuse.resetObjects();    if (ids == null)      return new Task[0];    Task[] tasks = new Task [ids.size()];    for (int i = 0; i < ids.size(); i++)      tasks[i] = sd.getTask ((String) ids.get(i));    return tasks;  }