@Override
 protected boolean doMatches(CreateSellOrderCommand command) {
   return command.getOrderBookId().equals(orderbookIdentifier)
       && command.getPortfolioId().equals(portfolioIdentifier)
       && tradeCount == command.getTradeCount()
       && itemPrice == command.getItemPrice();
 }
 @CommandHandler
 public void handleSellOrder(CreateSellOrderCommand command) {
   OrderBook orderBook = repository.load(command.getOrderBookId(), null);
   orderBook.addSellOrder(
       command.getOrderId(),
       command.getTransactionId(),
       command.getTradeCount(),
       command.getItemPrice(),
       command.getPortfolioId());
 }