@SuppressWarnings("unchecked")
    public static SaslExtensions empty() {
        // It's ok to re-use the EMPTY_MAP instance as the object equality is on the outer
        // SaslExtensions reference.
        return new SaslExtensions(Collections.EMPTY_MAP);
    }
Creates an "empty" instance indicating no SASL extensions. <em>Do not cache the result of
this method call</em> for use by multiple {@link Subject}s as the references need to be
unique.

<p/>

See the class-level documentation for details.
@return Unique, but empty, <code>SaslExtensions</code> instance
clients/src/main/java/org/apache/kafka/common/security/auth/SaslExtensions.java