public static void SetMetadata(this CloudBlob blob, string leaseId)
{
var req = BlobRequest.SetMetadata(new Uri(blob.ServiceClient.Credentials.TransformUri(blob.Uri.AbsoluteUri)), 90, leaseId);
foreach (string key in blob.Metadata.Keys)
{
req.Headers.Add("x-ms-meta-" + key, blob.Metadata[key]);
}
blob.ServiceClient.Credentials.SignRequest(req);
req.GetResponse().Close();
}