@Override
    public ElectionState election() {
        return ElectionState.withVotedCandidate(
            epoch,
            ReplicaKey.of(localId, localDirectoryId),
            voteStates.keySet()
        );
    }
Get the set of voters that have rejected our candidacy.

@return The set of rejecting voters
raft/src/main/java/org/apache/kafka/raft/CandidateState.java