private NodeCandidate.ExclusivityViolation violatesExclusivity(NodeCandidate candidate) {
        return candidate.violatesExclusivity(cluster, application,
                                             nodeRepository.exclusivity().clusterType(cluster),
                                             nodeRepository.exclusivity().allocation(cluster),
                                             nodeRepository.zone().cloud().allowHostSharing(), allNodes);
    }
Returns the cause of retirement for given candidate
node-repository/src/main/java/com/yahoo/vespa/hosted/provision/provisioning/NodeAllocation.java