synchronized String sourceTopicPatternString() {
        // With a NamedTopology, it may be that this topology does not use pattern subscription but another one does
        // in which case we would need to initialize the pattern string where we would otherwise have not
        if (sourceTopicPatternString == null) {
            sourceTopicPatternString = buildSourceTopicsPatternString();
        }
        return sourceTopicPatternString;
    }
@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