};

    /**
     * ScopeState
     */
    protected static final class ScopeState {
        private final Map<Key<?>, CachingProvider<?>> provided = new ConcurrentHashMap<>();

        public <T> void seed(Class<T> clazz, Provider<T> value) {
            provided.put(Key.get(clazz), new CachingProvider<>(value));
        }

        @SuppressWarnings("unchecked")
        public <T> Provider<T> scope(Key<T> key, Provider<T> unscoped) {