Dynamically named field on extern

I'm currently writing an extern for some js lib and I'm facing the following case:

```ts
type WrapOptions {
injectedPropName:String,
}
function wrapComponent(component:ReactType,?options:WrapOptions){
// ...
}
type WrappedComponentProps {
[injectedPropName]: InjectedShape
}
```

How could I type a prop with a dynamic name with Haxe 4.1? With a default value would be even better...