@Override
    public String toString() {
        return request.getShortDescription() + ", delayLeft=" + getDelay(TimeUnit.MILLISECONDS) + " ms";
    }
Class that handles responses that are put on delayedResponses queue.  Implements the <code>Delayed</code>
interface to keep track of the order of responses (used when checking
delayed responses and returning requests that are about to time out, in cases where no new
config has been returned from upstream)

@see DelayedResponseHandler
config-proxy/src/main/java/com/yahoo/vespa/config/proxy/DelayedResponse.java