When the withFlags(...) logic was modified to use a DecoratedCache instead of thread-local storage, any caches already decorated with the AbstractDelegatingAdvancedCache(...) broke.

Take the following code:
AdvancedCache<K, V> baseCache;
AdvancedCache<K, V> customCache = new AbstractDelegatingAdvancedCache<K, V>(baseCache) {
public void clear()

};

customCache.withFlags(Flag.CACHE_MODE_LOCAL).clear();

In the above statement, the flag is not applied.
The call to withFlags(...) returns a reference to customCache, and the reference to DecoratedCache containing the flags is lost to garbage collection.

In the case of with(ClassLoader) we have the opposite problem.

customCache.with(customClassLoader).clear();

In the above statement, the native clear() method is invoked instead of my custom clear() method. with(ClassLoader) returns a reference to DecoratedCache. The clear() method then operates on baseCache, instead of customCache.