A number of files in MongoDb.Core project are public even though they were not designed for that and effectively they're internal. But when we want to make a change in their "public" API we still try to avoid it which sometimes makes our code less clear.
However we already made some of these changes and no one complained about it during years. I think it would be good if we define which files(at least high-level) we can feel free to change and which ones not.

For example: `IAuthenticator` looks like a valid candidate to be effectively public since at least someone can want to moq this logic in their tests or implement his own logic, but it's hard to imagine if anyone can implement his own version of IChannel