@JsonAnyGetter
    public Map<String, PartitionsSpec> get() {
        return map;
    }
@Test
    public void testPartitionsSpec() throws Exception {
        String text = "{\"numPartitions\": 5, \"configs\": {\"foo\": \"bar\"}}";
        PartitionsSpec spec = JsonUtil.JSON_SERDE.readValue(text, PartitionsSpec.class);
        assertEquals(5, spec.numPartitions());
        assertEquals("bar", spec.configs().get("foo"));
        assertEquals(1, spec.configs().size());
    }