@Override
    public void close() {
        if ((t != null) && (t.isAlive())) {
            t.interrupt();
            try {
                t.join();
            } catch (InterruptedException e) {
                log.warn("[Principal={}]: Error while waiting for Login thread to shutdown.", principal, e);
                Thread.currentThread().interrupt();
            }
        }
    }
Performs login for each login module specified for the login context of this instance and starts the thread used
to periodically re-login to the Kerberos Ticket Granting Server.
clients/src/main/java/org/apache/kafka/common/security/kerberos/KerberosLogin.java