@Override
        public boolean equals(final Object o) {
            if (this == o) {
                return true;
            }
            if (o == null || getClass() != o.getClass()) {
                return false;
            }
            final Subtopology that = (Subtopology) o;
            return nodeGroupId == that.nodeGroupId &&
                    Objects.equals(namedTopology, that.namedTopology);
        }
@return the InternalTopologyBuilder for the NamedTopology with the given {@code topologyName}
        or the builder for a regular Topology if {@code topologyName} is {@code null},
        else returns {@code null} if {@code topologyName} is non-null but no such NamedTopology exists
streams/src/main/java/org/apache/kafka/streams/processor/internals/TopologyMetadata.java