public Principal peerPrincipal() {
        try {
            return sslEngine.getSession().getPeerPrincipal();
        } catch (SSLPeerUnverifiedException se) {
            log.debug("SSL peer is not authenticated, returning ANONYMOUS instead");
            return KafkaPrincipal.ANONYMOUS;
        }
    }
SSLSession's peerPrincipal for the remote host.
@return Principal
clients/src/main/java/org/apache/kafka/common/network/SslTransportLayer.java