public String getDocumentDBConfigId(String documentType) {
        DocumentDatabase db = documentDbs.get(documentType);
        if (db != null) {
            if (db.getDerivedConfiguration().isStreaming()) {
                return documentDBProducerForStreaming.get(documentType).getConfigId();
            } else {
                return db.getConfigId();
            }
        }
        return "";
    }
Returns the document databases contained in this cluster
config-model/src/main/java/com/yahoo/vespa/model/search/SearchCluster.java