public Set<Integer> grantingVoters() {
        return votersInState(State.GRANTED).map(ReplicaKey::id).collect(Collectors.toSet());
    }
Get the set of voters that have granted our vote requests.

@return The set of granting voters, which should always contain the ID of the candidate
raft/src/main/java/org/apache/kafka/raft/CandidateState.java