@Override
    public boolean canGrantVote(
        ReplicaKey candidateKey,
        boolean isLogUpToDate
    ) {
        // Still reject vote request even candidateId = localId, Although the candidate votes for
        // itself, this vote is implicit and not "granted".
        log.debug(
            "Rejecting vote request from candidate ({}) since we are already candidate in epoch {}",
            candidateKey,
            epoch
        );
        return false;
    }
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