private void buildIndexingClusters(Content content, ConfigModelContext modelContext,
                                           ApplicationConfigProducerRoot root) {
            var search = content.getCluster().getSearch();
            var indexingDocproc = search.getIndexingDocproc();
            if (indexingDocproc.hasExplicitCluster()) {
                setExistingIndexingCluster(content, indexingDocproc, content.containers);
            } else {
                setContainerAsIndexingCluster(search.getSearchNodes(), indexingDocproc, content, modelContext, root);
            }
        }
Select/creates and initializes the indexing cluster coupled to this
config-model/src/main/java/com/yahoo/vespa/model/content/Content.java