public Optional<Node> voterNode(int voterId, ListenerName listenerName) {
        return Optional.ofNullable(voters.get(voterId))
            .flatMap(voterNode -> voterNode.address(listenerName))
            .map(address -> new Node(voterId, address.getHostString(), address.getPort()));
    }
Returns the node information for a given voter id and listener.

@param voterId the id of the voter
@param listenerName the name of the listener
@return the node information if it exists, otherwise {@code Optional.empty()}
raft/src/main/java/org/apache/kafka/raft/internals/VoterSet.java