@SuppressWarnings("unchecked")
	public synchronized Object getKeyFromValue(Map<String, Map <Object, Long>> map, String key, Long id){

		if (map.get(key) == null)
			return null;

		for (Object o: map.get(key).entrySet()) {
			Map.Entry<Object,Long> entry = (Map.Entry<Object, Long>) o;
			if(entry.getValue().equals(id))
				return entry.getKey();
		}
		return null;
	}