code: public List<SimulatorEvent> init(long when) {
      LOG.debug("TaskTracker starting up, current simulation time=" + when);
  
      return Collections.<SimulatorEvent>singletonList(new HeartbeatEvent(this, when));  
    }
docs: Called once at the start of the simulation.
  
  @param when Time when the task tracker starts.
  @return the initial HeartbeatEvent for ourselves.