oci/archive/oci_transport.go
func (ref ociArchiveReference) StringWithinTransport() string {
	return fmt.Sprintf("%s:%s", ref.file, ref.image)
}
func (ref ociArchiveReference) StringWithinTransport() string {
	return fmt.Sprintf("%s:%s", ref.file, ref.image)
}
// StringWithinTransport returns a string representation of the reference, which MUST be such that
// reference.Transport().ParseReference(reference.StringWithinTransport()) returns an equivalent reference.