public Map<String, PartitionsSpec> materialize() {
        HashMap<String, PartitionsSpec> all = new HashMap<>();
        for (Map.Entry<String, PartitionsSpec> entry : map.entrySet()) {
            String topicName = entry.getKey();
            PartitionsSpec partitions = entry.getValue();
            for (String expandedTopicName : StringExpander.expand(topicName))
                all.put(expandedTopicName, partitions);
        }
        return all;
    }
@Test
    public void testMaterialize() {
        Map<String, PartitionsSpec> parts = FOO.materialize();
        assertTrue(parts.containsKey("topicA0"));
        assertTrue(parts.containsKey("topicA1"));
        assertTrue(parts.containsKey("topicA2"));
        assertTrue(parts.containsKey("topicB"));
        assertEquals(4, parts.keySet().size());
        assertEquals(PARTSA, parts.get("topicA0"));
        assertEquals(PARTSA, parts.get("topicA1"));
        assertEquals(PARTSA, parts.get("topicA2"));
        assertEquals(PARTSB, parts.get("topicB"));
    }