void BundlesChanged(object sender, BundleCollectionChangedEventArgs e)
 {
     // Multiple concurrent bundle change events could cause problems.
     // So lock to avoid race conditions
     lock (urlLock)
     {
         Url = BuildUrl();
     }
 }
 void BundlesChanged(object sender, BundleCollectionChangedEventArgs e)
 {
     // Multiple concurrent bundle change events could cause problems.
     // So lock to avoid race conditions
     lock (urlLock)
     {
         Url = BuildUrl();
     }
 }