private String createTopic(final int suffix) throws InterruptedException {
        final String outputTopic = "outputTopic_" + suffix;
        CLUSTER.createTopic(outputTopic);
        return outputTopic;
    }
End-to-end integration test based on using regex and named topics for creating sources, using
an embedded Kafka cluster.
streams/src/test/java/org/apache/kafka/streams/integration/RegexSourceIntegrationTest.java