public Map<String, Map<Subtopology, TopicsInfo>> topologyToSubtopologyTopicsInfoMap() {
        final Map<String, Map<Subtopology, TopicsInfo>> topologyToSubtopologyTopicsInfoMap = new HashMap<>();
        applyToEachBuilder(b -> topologyToSubtopologyTopicsInfoMap.put(b.topologyName(), b.subtopologyToTopicsInfo()));
        return  topologyToSubtopologyTopicsInfoMap;
    }
@return    map from topology to its subtopologies and their topics info
streams/src/main/java/org/apache/kafka/streams/processor/internals/TopologyMetadata.java