@Override
        protected ArrayList<AssetKey> initialValue() {
            return new ArrayList<>();
        }
Stores the original key and original asset.
The asset info contains a cloneable asset (e.g. the original, from
which all clones are made) and also a weak reference to the
original key, which is used when the clones are produced.
jme3-core/src/main/java/com/jme3/asset/cache/WeakRefCloneAssetCache.java