@Override
    public void close() {
    }
Default callback handler for Sasl servers. The callbacks required for all the SASL
mechanisms enabled in the server should be supported by this callback handler. See
<a href="https://docs.oracle.com/javase/8/docs/technotes/guides/security/sasl/sasl-refguide.html">Java SASL API</a>
for the list of SASL callback handlers required for each SASL mechanism.
clients/src/main/java/org/apache/kafka/common/security/authenticator/SaslServerCallbackHandler.java