return type;
    }

    private Collection<E> getBackingValue() {
        return Cast.uncheckedCast(modelNode.getPrivateData(Collection.class));
    }

    private void setBackingValue(Collection<E> values) {
        if (state.isCanMutate()) {
            modelNode.setPrivateData(Collection.class, values);
        }
    }

    protected abstract C toMutationSafe(Collection<?> backingCollection);