> The google.golang.org/protobuf module is APIv2. We have taken advantage of the need to change the import path to switch to one that is not tied to a specific hosting provider.

This seems like a good example why tying the name of the package in the code with the place where it can be downloaded was a very bad idea. Simply changing hosting providers is now a backwards compatibility break for your clients.

If Go imports didn't work this way, you could have simply offered the old v1 from both github.com and google.golang.org, and used a clear v2 for the v2. Sure , you would have similar problems if you wanted to change the logical package structure for some reason (say, when an open-source package moves to a different organization), but that is a much rarer case than switching code repos.

However, given that that ship has probably long sailed, you probably picked the right choice.

I would also note that v2 in the import path feels a bit strange, since it makes users of the newest code need to know about the history of the package, but there are also clear advantages which probably out-weigh this (I believe this is absolutely not the case for the decision to include the hosting provider in the import path).