Iterator<ClientRequest> requestIterator(Node node) {
            ArrayDeque<ClientRequest> requests = unsent.get(node);
            return (requests == null) ? Collections.emptyIterator() : requests.iterator();
        }
An inter-broker send thread that utilizes a non-blocking network client.
server-common/src/main/java/org/apache/kafka/server/util/InterBrokerSendThread.java