Make Descriptor an alias for oci.Descriptor

With the removal of the Describable interface from this type, and
deprecation of the Versioned type, the Descriptor is now an exact
equivalent of the oci.Descriptor.

This patch makes Descriptor an alias for oci.Descriptor.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

blobs.go

@@ -46,7 +46,7 @@ func (err ErrBlobInvalidDigest) Error() string {
 // instead of initiating an upload session.
 type ErrBlobMounted struct {
 	From       reference.Canonical
-	Descriptor Descriptor
+	Descriptor v1.Descriptor
 }
 
 func (err ErrBlobMounted) Error() string {
@@ -58,32 +58,9 @@ func (err ErrBlobMounted) Error() string {
 // store, a descriptor can be used to fetch, store and target any kind of
 // blob. The struct also describes the wire protocol format. Fields should
 // only be added but never changed.
-type Descriptor struct {
-	// MediaType describe the type of the content. All text based formats are
-	// encoded as utf-8.
-	MediaType string `json:"mediaType,omitempty"`
-
-	// Digest uniquely identifies the content. A byte stream can be verified
-	// against this digest.
-	Digest digest.Digest `json:"digest,omitempty"`
-
-	// Size in bytes of content.
-	Size int64 `json:"size,omitempty"`
-
-	// URLs contains the source URLs of this content.
-	URLs []string `json:"urls,omitempty"`
-
-	// Annotations contains arbitrary metadata relating to the targeted content.
-	Annotations map[string]string `json:"annotations,omitempty"`
-
-	// Platform describes the platform which the image in the manifest runs on.
-	// This should only be used when referring to a manifest.
-	Platform *v1.Platform `json:"platform,omitempty"`
-
-	// NOTE: Before adding a field here, please ensure that all
-	// other options have been exhausted. Much of the type relationships
-	// depend on the simplicity of this type.
-}
+//
+// Descriptor is an alias for [v1.Descriptor].
+type Descriptor = v1.Descriptor
 
 // BlobStatter makes blob descriptors available by digest. The service may
 // provide a descriptor of a different digest if the provided digest is not