DownloadScheme instances are managed in a DynamicMap, so add support for that in ExtensionRegistry, and modify the test to use it. Change-Id: I6111bbf3935fc223a63f0533e7b6c285f2fd2ae3
DownloadScheme instances are managed in a DynamicMap, so add support for that in ExtensionRegistry, and modify the test to use it. Change-Id: I6111bbf3935fc223a63f0533e7b6c285f2fd2ae3