public Collection<ClientRequest> remove(Node node) {
            // the lock protects removal from a concurrent put which could otherwise mutate the
            // queue after it has been removed from the map
            synchronized (unsent) {
                ConcurrentLinkedQueue<ClientRequest> requests = unsent.remove(node);
                return requests == null ? Collections.emptyList() : requests;
            }
        }
Return whether the caller is still awaiting an IO event.
@return true if so, false otherwise.
clients/src/main/java/org/apache/kafka/clients/consumer/internals/ConsumerNetworkClient.java