public Collection<Set<String>> copartitionGroups() {
        final List<Set<String>> copartitionGroups = new ArrayList<>();
        applyToEachBuilder(b -> copartitionGroups.addAll(b.copartitionGroups()));
        return copartitionGroups;
    }
@return    map from topology to its subtopologies and their topics info
streams/src/main/java/org/apache/kafka/streams/processor/internals/TopologyMetadata.java