I'd love for it to be `google.redacted` since they define the other common message types. But I think it'll be a while til we have that, so in the interim I think it wants to be `squareup.redacted` for Square.

I suggested Matt explicitly not call it `squareup.redacted` because I'm reluctant to distribute a `.proto` file with Wire. Is that a mistake? Perhaps we should just make `squareup.redacted` work and use that exclusively.