private String start(
      String key, boolean enableHighAccuracy, int timeout, int maximumAge, String deviceAddress) {
    MindSetListener listener = this.mindsetListeners.get(key);
    if (listener == null) {
      listener = new MindSetListener(this, key, timeout, deviceAddress);
      this.mindsetListeners.put(key, listener);
    }

    listener.start(maximumAge);
    return key;
  }
 @Override
 public void onDestroy() {
   Set<Entry<String, MindSetListener>> s = this.mindsetListeners.entrySet();
   Iterator<Entry<String, MindSetListener>> it = s.iterator();
   while (it.hasNext()) {
     Map.Entry<String, MindSetListener> entry = it.next();
     MindSetListener listener = (MindSetListener) entry.getValue();
     listener.destroy();
   }
   this.mindsetListeners.clear();
 }
 private void stop(String key) {
   MindSetListener listener = this.mindsetListeners.remove(key);
   if (listener != null) listener.stop();
 }