@Test
    public void nullValuesAreNotUnwrapped() {
        Configuration config = new ConfigurationBuilder().build();
        SpringEmbeddedCacheManager cacheManager = new SpringEmbeddedCacheManager(new DefaultCacheManager(config));
        SpringCache cache = cacheManager.getCache("foo");
        cache.put("nullable", null);
        assertNull(cache.get("nullable", () -> "a"));
    }