Cache configured with the new configuration always returns null values

The test case:

DefaultCacheManager cacheManager = new DefaultCacheManager(new ConfigurationBuilder().build());

Cache<String, String> cache = cacheManager.getCache();
cache.put("Foo", "2");
cache.put("Bar", "4");

System.out.println(cache.get("Foo"));
System.out.println(cache.get("Bar"));