private static void validate(ClusterResources resources) {
        if (resources.nodes() == 0 && resources.groups() == 0) return; // unspecified
        if (resources.nodes() % resources.groups() != 0)
            throw new IllegalArgumentException("The number of nodes (" + resources.nodes() +
                                               ") must be divisible by the number of groups (" + resources.groups() + ")");
    }
Resources should stay between these values, inclusive
config-provisioning/src/main/java/com/yahoo/config/provision/Capacity.java