How to use C# 8.0 Nullable Reference Types with Entity Framework Core models?

There is no proper way to handle non-nullable navigational properties.

1. Documentation suggests two ways and both are not type safe. Use a
   backing field and throw InvalidOperationException. It is unclear how
   it differs from doing nothing and have a NullReferenceException
2. Suppress it with null forgiving operator

Official documentation link: https://learn.microsoft.com/en-us/ef/core/miscellaneous/nullable-reference-types#non-nullable-properties-and-initialization