Only trading players with certain items?

[dirtrider478 12]

Im currently using this to trade

    @Override
    public void onTradeMessage(Message arg0) {
        String trader= arg0.getUsername();
        getTrade().tradeWithPlayer(trader);
        sleep(Calculations.random(500, 1200));

Im wondering if theres a way to ether define the string trader with requiring the player to have items equipped or is there a way to only trade trader if he has specific items equipped. Any help is appreciated.