Add state parameter manually in authorize request

[lsuhov]

Hello, We are having a scenario where we wanted to temporarily assign a fixed state as parameter. While trying to add the state field in additionalParameters, in Android we got the following Platform exception: "Parameter state is directly supported via the authorization request builder, use the builder method instead"

We then concluded that this functionality is feasible at native library level, but not on Flutter library level.

Is it possible to expose this in Flutter library? Thank you

[MaikuB]

Please submit a PR if you are in need of this. Another member of the community attempted to do so before in https://github.com/MaikuB/flutter_appauth/pull/96 but I closed the PR as there were no updates to fix the failing tests

[sonufrienko]

I have the same issue

[MaikuB]

Closing this as anyone interested in this can look to submit a PR and there's been further updates to one that had been opened before