@Override
    public void getConfig(ClusterListConfig.Builder builder) {
        VespaModel model = (VespaModel) getRoot();
        for (ContentCluster cluster : model.getContentClusters().values()) {
            ClusterListConfig.Storage.Builder storage = new ClusterListConfig.Storage.Builder();
            storage.name(cluster.getName());
            storage.configid(cluster.getConfigId());
            builder.storage(storage);
        }
    }
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