restore(string) --
If the object is an archived object (an object whose storage class is GLACIER), the response includes this header if either the archive restoration is in progress (see RestoreObject or an archive copy is already restored.
If an archive copy is already restored, the header value indicates when Amazon S3 is scheduled to delete the object copy. For example:
x-amz-restore: ongoing-request="false", expiry-date="Fri, 21 Dec 2012 00:00:00 GMT"
If the object restoration is in progress, the header returns the value ongoing-request="true" .
For more information about archiving objects, see Transitioning Objects: General Considerations.