public boolean allocation(ClusterSpec clusterSpec) {
        return clusterSpec.isExclusive() ||
               ( clusterSpec.type().isContainer() && zone.system().isPublic() && !zone.environment().isTest() ) ||
               ( !zone.cloud().allowHostSharing() && !sharedHost.supportsClusterType(clusterSpec.type()));
    }
Returns whether nodes are allocated exclusively in this instance given this cluster spec.
Exclusive allocation requires that the wanted node resources matches the advertised resources of the node
perfectly.
config-provisioning/src/main/java/com/yahoo/config/provision/Exclusivity.java