@Override
        public String toString() {
            final String topicsString = topics == null ? topicPattern.toString() : topics.toString();

            return "Source: " + name + " (topics: " + topicsString + ")\n      --> " + nodeNames(successors);
        }
@return names of all source topics, including the application id/named topology prefix for repartition sources
streams/src/main/java/org/apache/kafka/streams/processor/internals/InternalTopologyBuilder.java