General things:

• Keep the PR short. This is already long and needs to be shrinked.
• Avoid pressing the hotkey to reorder imports as they generate excessive and unnecessary diff. Rollback those changes if possible.
• Don't change the logic of the existing tests. They are there for a reason.
• Either use the constants on the tests or on the exported classes, not in both.
• Don't export files you don't want people to have
• Don't add methods that throw an exception because "they shouldn't be called".

Important one: Any public API changes are to be discussed with the team. Pause the coding and create a doc to discuss this.