Correct nullability annotations in OIDEndSessionRequest

[philet]

Correct nullability annotations for OIDEndSessionRequest parameters idTokenHint, postLogoutRedirectURL, and state.

Fixes #565

[petea]

@philet have you signed the contributor agreements?

[philet]

@petea I have signed them last Friday. Probably still needs to be processed on your side.

[petea]

@philet confirmed that we have the needed documentation from you, thanks.

[petea]

Since this will be a breaking change for the Swift interface, we'll need to make it as part of a major release.

[nbransby]

@petea since its only adding the nullability won't existing code still compile meaning its not a breaking change?

[pfei5]

We're having to run a fork of this lib because of this issue. Is there anything missing from the PR that we could provide?

[matax87]

Any update on this?

[trykovyura]

up

[MichaelHackett]

@petea: Please provide an update. Is @nbransby correct about it not being a breaking change? I'd rather not have to maintain a fork of the library just to address this one issue, so I'd like to see this finally accepted and merged. It looks to me like it wasn't even changed in the 2.0.0 release, where a breaking change (if it actually is) could have been made.