[PAGE ISSUE]: Example on breaking change page should be updated to be null safe

[abinvs-2019]

Page URL

https://docs.flutter.dev/release/breaking-changes/parent-data-widget-generic-type/

Page source

https://github.com/flutter/website/tree/main/src/release/breaking-changes/parent-data-widget-generic-type.md

Describe the problem

@required was changed to required

Expected fix

Change the @ symbol from @required to required

Additional context

No response

[danagbemava-nc]

Thanks for pointing that out.

It appears the code sample on that page hasn't been updated for null-safety yet.

[sfshaza2]

@khanhnwin, fyi