protected IEnumerable<Bundle> CreateExternalBundlesUrlReferences(Bundle[] bundlesArray) { var existingUrls = bundlesArray.OfType<IExternalBundle>().Select(b => b.Url); var generator = new ExternalBundleGenerator(existingUrls, settings); foreach (var bundle in bundlesArray) { bundle.Accept(generator); } return generator.ExternalBundles; }