public void add(NetworkClient.InFlightRequest request) {
        String destination = request.destination;
        Deque<NetworkClient.InFlightRequest> reqs = this.requests.computeIfAbsent(destination, k -> new ArrayDeque<>());
        reqs.addFirst(request);
        inFlightRequestCount.incrementAndGet();
    }
Add the given request to the queue for the connection it was directed to
clients/src/main/java/org/apache/kafka/clients/InFlightRequests.java