private List<LoadBalancer> surplusLoadBalancersOf(ApplicationId application, Set<ClusterSpec.Id> activeClusters) {
        var activeLoadBalancersByCluster = nodeRepository.loadBalancers().list(application)
                                                         .in(LoadBalancer.State.active)
                                                         .asList()
                                                         .stream()
                                                         .collect(Collectors.toMap(lb -> lb.id().cluster(),
                                                                                   Function.identity()));
        var surplus = new ArrayList<LoadBalancer>();
        for (var kv : activeLoadBalancersByCluster.entrySet()) {
            if (activeClusters.contains(kv.getKey())) continue;
            surplus.add(kv.getValue());
        }
        return Collections.unmodifiableList(surplus);
    }
Returns load balancers of given application that are no longer referenced by given clusters
node-repository/src/main/java/com/yahoo/vespa/hosted/provision/provisioning/LoadBalancerProvisioner.java