class AssetGroupManager {

    public void addAsset(Asset asset) {
        AssetGroup group = _groups.get(asset.getGroup() + "-" + asset.getType());
        if (group == null) {
            throw new IllegalArgumentException("AssetGroup does not exist for asset " + asset);
        }
        group.addAsset(asset);
    }

    public  AssetGroupManager();

}