@Override
    public void validate(ChangeContext context) {
        // Skip for tester applications
        if (context.previousModel().applicationPackage().getApplicationId().instance().isTester()) return;
        context.previousModel().getContainerClusters()
                .forEach((clusterId, currentCluster) -> {
                    if(context.model().getContainerClusters().containsKey(clusterId))
                        validateClients(clusterId,
                                        currentCluster.getClients(),
                                        context.model().getContainerClusters().get(clusterId).getClients(),
                                        context::invalid);
                });
    }
Check that data plane certificates are not removed from a cluster.

@author mortent
config-model/src/main/java/com/yahoo/vespa/model/application/validation/change/CertificateRemovalChangeValidator.java