public void setupRouting(DeployState deployState, VespaModel vespaModel, ConfigModelRepo configModels) {
        if (admin != null) {
            Routing routing = configModels.getRouting();
            if (routing == null) {
                routing = new Routing(ConfigModelContext.create(deployState, vespaModel, configModels, this, "routing"));
                configModels.add(routing);
            }
            this.routing = routing;
        }
    }
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