Merge remote-tracking branch 'origin/feat/repository-mounting' into f…

…eat/repository-mounting

src/OrasProject.Oras/Registry/Remote/Repository.cs

@@ -347,6 +347,6 @@ internal Reference ParseReferenceFromContentReference(string reference)
     /// <param name="getContent"></param>
     /// <param name="cancellationToken"></param>
     /// <returns></returns>
-    public async Task MountAsync(Descriptor descriptor, string fromRepository, Func<CancellationToken, Task<Stream>>? getContent, CancellationToken cancellationToken = default) 
+    public async Task MountAsync(Descriptor descriptor, string fromRepository, Func<CancellationToken, Task<Stream>>? getContent = null, CancellationToken cancellationToken = default) 
         => await ((IMounter)Blobs).MountAsync(descriptor, fromRepository, getContent, cancellationToken).ConfigureAwait(false);
 }