@Override
        public void doBuild(ContentModelAmender model, Element spec, ConfigModelContext modelContext) {
            if (built) return; // the same instance will be called once per content cluster
            for (Content contentModel : model.contentModels)
                contentModel.ownedIndexingCluster().ifPresent(ContainerModelAmenderBuilder::amend);
            built = true;
        }
The container models this builder amends
config-model/src/test/java/com/yahoo/vespa/model/test/ModelAmendingTestCase.java