List<DelayedConfigResponse> drainQueue(ApplicationId app) {
        ArrayList<DelayedConfigResponse> ret = new ArrayList<>();
        
        if (delayedResponses.containsKey(app)) {
            BlockingQueue<DelayedConfigResponse> queue = delayedResponses.get(app);
            queue.drainTo(ret);
        }
        metrics.remove(app);
        return ret;
    }
Drains delayed responses queue and returns responses in an array

@return and array of DelayedConfigResponse objects
configserver/src/main/java/com/yahoo/vespa/config/server/rpc/DelayedConfigResponses.java