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