@Override
        public Optional<KafkaPrincipalSerde> principalSerde() {
            return principalBuilder instanceof KafkaPrincipalSerde ? Optional.of((KafkaPrincipalSerde) principalBuilder) : Optional.empty();
        }
Constructs Principal using configured principalBuilder.
@return the built principal
clients/src/main/java/org/apache/kafka/common/network/SslChannelBuilder.java