Mockito with Java async->sync converter

I have an async method I am converting to a sync method using a countdown latch. I'm struggling with writing a unit test without using mockito's timeout function. I can't work out how to get the verify method to wait for the async method call:

public interface SyncExchangeService {
    boolean placeOrder(Order order);
}
public interface ExchangeService {
    void placeOrder(Order order, OrderCallback orderResponseCallback);
}

public interface OrderCallback {
    public void onSuccess();
    public void onFailure();
}



public class SyncExchangeServiceAdapter implements SyncExchangeService {
    private ExchangeService exchangeService;

    public SyncExchangeServiceAdapter(ExchangeService exchangeService) {
        this.exchangeService = exchangeService;
    }

    @Override
    public boolean placeOrder(Order order) {

        final CountDownLatch countdownLatch=new CountDownLatch(1);
        final AtomicBoolean result=new AtomicBoolean();
        exchangeService.placeOrder(order, new OrderCallback() {

            @Override
            public void onSuccess() {
                result.set(true);
                countdownLatch.countDown();
            }

            @Override
            public void onFailure(String rejectReason) {
                result.set(false);
                countdownLatch.countDown();
            }
        });
        try {
            countdownLatch.await();
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }
        return result.get();
    }
}


public class SyncExchangeServiceAdapterTest {
    private ExchangeService mockExchange=mock(ExchangeService.class);
    private SyncExchangeServiceAdapter adapter=new SyncExchangeServiceAdapter(mockExchange);
    private Boolean response;
    private ArgumentCaptor<Boolean> callback=CaptorArgumentCaptor.forClass(OrderCallback.class);
    private CountDownLatch latch=new CountDownLatch(1);


    @Test
    public void testPlaceOr