private void sendNoReceive(KafkaChannel channel, int numRequests) throws Exception {
        selector.mute(channel.id());
        for (int i = 0; i < numRequests; i++) {
            selector.send(createSend(channel.id(), String.valueOf(i)));
            do {
                selector.poll(10);
            } while (selector.completedSends().isEmpty());
        }
        selector.unmute(channel.id());
    }
Sends the specified number of requests and waits for the requests to be sent.
The channel is muted during polling to ensure that incoming data is not received.
clients/src/test/java/org/apache/kafka/common/network/SelectorTest.java