abstract class NodeBackedModelMapSpec<T extends Named, S extends Special & T> extends ProjectRegistrySpec {
    abstract Class<T> getItemClass()
    abstract Class<S> getSpecialItemClass()
    ModelType<T> getItemType() { ModelType.of(itemClass) }
    ModelType<S> getSpecialItemType() { ModelType.of(specialItemClass) }
    ModelPath path = ModelPath.path("map")

    ModelType<ModelMap<T>> getModelMapType() {