@Override
 public boolean confirm(Exchange exchange, String key) {
   exchanges.add(exchange.getExchangeId());
   return delegate.confirm(key);
 }
 @Override
 public void clear() {
   delegate.clear();
 }
 @Override
 public boolean remove(Exchange exchange, String key) {
   exchanges.add(exchange.getExchangeId());
   return delegate.remove(key);
 }