code: public void update(LimitOrder limitOrder) {
  
      update(getOrders(limitOrder.getType()), limitOrder);
      updateDate(limitOrder.getTimestamp());
    }
docs: Given a new LimitOrder, it will replace a matching limit order in the orderbook if one is
  found, or add the new LimitOrder if one is not. timeStamp will be updated if the new timestamp
  is non-null and in the future.
  
  @param limitOrder the new LimitOrder