@Override
    public String toString() {
        return toString("");
    }
@Test
    public void shouldCreateStringWithMultipleSourcesAndTopics() {
        topology.addSource("source", "topic1", "topic2");
        topology.addSource("source2", "t", "t1", "t2");
        final ProcessorTopology processorTopology = topology.getInternalBuilder().buildTopology();
        final String result = processorTopology.toString();
        assertThat(result, containsString("source:\n\t\ttopics:\t\t[topic1, topic2]\n"));
        assertThat(result, containsString("source2:\n\t\ttopics:\t\t[t, t1, t2]\n"));
    }