@Override
    public void getConfig(ModelConfig.Builder builder) {
        builder.vespaVersion(vespaVersion.toFullString());
        for (HostResource modelHost : hostSystem().getHosts()) {
            builder.hosts(new Hosts.Builder()
                    .name(modelHost.getHostname())
                    .services(getServices(modelHost))
            );
        }
    }
Prepares the model for start. The {@link VespaModel} calls
this methods after it has loaded this and all plugins have been loaded and
their initialize() methods have been called.

@param plugins All initialized plugins of the vespa model.
config-model/src/main/java/com/yahoo/config/model/ApplicationConfigProducerRoot.java