When a new API is added, we're obligated to preserve backwards compatibility. However, sometimes it's hard to nail the correct API in the first shot, which creates a problem.
To mitigate this, we're adding an @ExperimentalApi annotation, which can be used on new APIs to let users and customers know we encourage them to use it and provide feedback, but they're still subject to changes.
For developers considering using this annotation - note that some users will be discouraged by it, and will not use an experimental API - do strive to use it only when appropriate and not by default.
Nothing to test - merely added an annotation