Nullable Reference Types

[lechu445]

Is your feature request related to a problem? Please describe.

Let's add NRT annotations. There are many articles explaining what benefits it bring.

Describe the solution you'd like

This change is possible to split into 2 changes:

• to mark public API with NRT (breaking change)
• add NRT to internal code

Describe alternatives you've considered

No response

Additional context

This would be a breaking change, as marking public API with NRT can cause warnings in users projects. If they have TreatWarningsAsErrors, this can cause their projects not built. Therefore, let's consider it as a breaking change.

[lukebakken]

Please feel free to provide a pull request to implement this.

Version 7 is slated to be released soon, so this will have to go into version 8.

[lukebakken]

@lechu445 please note that @bollhals has undertaken your request. I suggest you show your appreciation, because he has done a LOT of work.

[lechu445]

Thanks @lukebakken for the update and thanks @bollhals for the PR. I will review your change to compare my current work with yours. Thanks a lot!