public static MapperReference getMapper() {
        return MAPPER_REFERENCE.get();
    }
@Test
    public void testMetricsMixIn() {
        ObjectMapper objectMapper = ObjectMapperFactory.getMapper().getObjectMapper();
        try {
            Metrics metrics = new Metrics();
            String json = objectMapper.writeValueAsString(metrics);
            Assert.assertTrue(json.contains("dimensions"));
        } catch (Exception ex) {
            Assert.fail("shouldn't have thrown exception", ex);
        }
    }