public static boolean isUnavailable(KafkaClient client, Node node, Time time) {
        return client.connectionFailed(node) && client.connectionDelay(node, time.milliseconds()) > 0;
    }
Check if the code is disconnected and unavailable for immediate reconnection (i.e. if it is in
reconnect backoff window following the disconnect).
clients/src/main/java/org/apache/kafka/clients/NetworkClientUtils.java