private static void ImportAsset(string file, AssetBundle sourceBundle, AssetBundle destinationBundle)
 {
     using (var stream = sourceBundle.OpenFileRaw(file)) {
         destinationBundle.ImportFileRaw(
             file, stream, 0,
             sourceBundle.GetSourceExtension(file),
             sourceBundle.GetFileLastWriteTime(file),
             sourceBundle.GetAttributes(file),
             sourceBundle.GetCookingRulesSHA1(file));
     }
 }
 public override DateTime GetFileLastWriteTime(string path) => Bundle.GetFileLastWriteTime(path);