How to build a native plugin with multiple platform support?

I'm trying to make a native plugin for multiple platforms, but the unity project generator keeps putting the wrong libraries into my xcode projects.

I have the following:

• Assets/Plugins/MyPlugin.bundle

• Assets/Plugins/iOS/MyPlugin.a

• Assets/Plugins/tvOS/MyPlugin.framework

If I build for desktop (mac), all is well.

If I build for tvOS, the resulting Xcode project has MyPlugin.framework (good) and MyPlugin.bundle (bad). The bundle contains Mac code, so obviously it won't work in an Apple TV project!

If I build for iOS, it's even worse, because it includes all three in the project!

How should I set things up so that they just work for whatever platform you want to deploy on?