Fully implement nullable support in Identity templates.

[blowdart]

Identity templates are not yet compatible with the ongoing nullable work.

After the 5.0 release we should go through everything and make sure it works.

For example,

#24201
#24165
#22656

[ghost]

Thanks for contacting us.

We're moving this issue to the .NET 8 Planning milestone for future evaluation / consideration. We would like to keep this around to collect more feedback, which can help us with prioritizing this work. We will re-evaluate this issue, during our next planning meeting(s).
If we later determine, that the issue has no community involvement, or it's very rare and low-impact issue, we will close it - so that the team can focus on more important and high impact issues.
To learn more about what to expect next and how this issue will be handled you can read more about our triage process here.

[BForderRP]

Please don't kick the can 2 major versions down the road on fixing this. dotNET 6 needs this fix.

[mikekistler]

All specific instances mentioned here appear to be fixed, so we're closing this as done. But if there are any other instances please open a new issue for this.