Currently, all filter configs use "name" to lookup an extension. We would like to use "name" for other purposes (e.g. a key in xDS just like all other resources). For that to happen, we would like to be able to load an extension using the config type URL, with a few caveats:

• deprecated Struct not supported (require TypedStruct)
• deprecated google.protobuf.Empty configs are not supported

In case it's not supported, we will fallback to name as the mechanism to lookup a filter factory.
@htuch