private void sendAuthenticationFailureResponse() throws IOException {
        if (authenticationFailureSend == null)
            return;
        sendKafkaResponse(authenticationFailureSend);
        authenticationFailureSend = null;
    }
Send any authentication failure response that may have been previously built.
clients/src/main/java/org/apache/kafka/common/security/authenticator/SaslServerAuthenticator.java