@Override
    public LoadBalancerInstance configure(LoadBalancerInstance instance, LoadBalancerSpec spec, boolean force) {
        return instance.with(spec.reals(), spec.settings(), Optional.empty());
    }
This implementation of {@link LoadBalancerService} returns the load balancer(s) that exist by default in the shared
routing layer.
<p>
Since such load balancers always exist, we can return the hostname of the routing layer VIP directly. Nothing has to
be provisioned.

@author ogronnesby
node-repository/src/main/java/com/yahoo/vespa/hosted/provision/lb/SharedLoadBalancerService.java