@Override
        public String toString() {
            if (topicNameExtractor instanceof StaticTopicNameExtractor) {
                return "Sink: " + name + " (topic: " + topic() + ")\n      <-- " + nodeNames(predecessors);
            }
            return "Sink: " + name + " (extractor class: " + topicNameExtractor + ")\n      <-- "
                + nodeNames(predecessors);
        }
@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