@Override
    public LeaderAndEpoch leaderAndEpoch() {
        if (isInitialized()) {
            return quorum.leaderAndEpoch();
        } else {
            return LeaderAndEpoch.UNKNOWN;
        }
    }
Create a new instance.

Note that if the node ID is empty, then the client will behave as a
non-participating observer.
raft/src/main/java/org/apache/kafka/raft/KafkaRaftClient.java