private String blockingRequest(String node, String s) throws IOException {
        selector.send(createSend(node, s));
        while (true) {
            selector.poll(1000L);
            for (NetworkReceive receive : selector.completedReceives())
                if (receive.source().equals(node))
                    return asString(receive);
        }
    }
Validate that correct subset of io metrics marked deprecated in docs
clients/src/test/java/org/apache/kafka/common/network/SelectorTest.java