private void poll(Selector selector) {
        try {
            selector.poll(50);
        } catch (IOException e) {
            throw new RuntimeException("Unexpected failure during selector poll", e);
        }
    }
Tests client connection close before response for authentication failure is sent.
clients/src/test/java/org/apache/kafka/common/security/authenticator/SaslAuthenticatorFailureDelayTest.java