public <S extends T> Class<S> getOtherType() {
        return d.class as Class<S>
    }

    List<T> iterationOrder(T... elements) {
        return elements
    }

    abstract boolean isExternalProviderAllowed()

    abstract boolean isDirectElementAdditionAllowed()

    abstract boolean isElementRemovalAllowed()

    void containerAllowsElementAddition() {