public synchronized Topology addSource(final String name,
                                           final String... topics) {
        internalTopologyBuilder.addSource(null, name, null, null, null, topics);
        return this;
    }
@Test
    public void shouldNotAllowToAddTopicTwice() {
        topology.addSource("source", "topic-1");
        try {
            topology.addSource("source-2", "topic-1");
            fail("Should throw TopologyException for already used topic");
        } catch (final TopologyException expected) { }
    }