@Override
    public void clearCache() {
        ArrayList<AssetKey> loadStack = assetLoadStack.get();

        if (!loadStack.isEmpty()) {
            throw new UnsupportedOperationException("Cache cannot be modified"
                    + "while assets are being loaded");
        }

        smartCache.clear();
    }
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