public Map<String, ApplicationContainerCluster> getContainerClusters() {
        Map<String, ApplicationContainerCluster> clusters = new LinkedHashMap<>();
        for (ContainerModel model : configModelRepo.getModels(ContainerModel.class)) {
            if (model.getCluster() instanceof ApplicationContainerCluster) {
                clusters.put(model.getId(), (ApplicationContainerCluster) model.getCluster());
            }
        }
        return Collections.unmodifiableMap(clusters);
    }
Returns a map of container clusters by ID
config-model/src/main/java/com/yahoo/vespa/model/VespaModel.java