thrown(ConcurrentModificationException)
    }

    ProviderInternal<? extends String> provider(String value) {
        return new TypedProvider(String, value)
    }

    ProviderInternal<? extends StringBuffer> provider(StringBuffer value) {
        return new TypedProvider(StringBuffer, value)
    }

    CollectionProviderInternal<? extends String, Set<? extends String>> setProvider(String... values) {