lastAssignment = null; lastNewGroup = false;
  public void addGroupedContrib (Assignment a, MultitaskAssignment ma) {    lastAssignment = null;    lastNewGroup = false;    if (ma != null)      ma.addTask (a.getTask());    else      schedule.add (new MultitaskAssignment                    (new Task[] {a.getTask()}, this,                     a.getTask().getCapacityContribs(), a.getStartTime(),                     a.getTaskStartTime(), a.getTaskEndTime(),                     a.getEndTime(), timeOps));  }