Cannot convert null literal to non-nullable reference type.

Nullability of reference types in return type of 'Task<PostalInformationResponse?> GrarClient.GetPostalInformation(string postcode)' doesn't match implicitly implemented member 'Task<PostalInformationResponse> IGrarClient.GetPostalInformation(string postcode)'.

'Postnamen.Empty' hides inherited member 'ReadOnlyCollection<Postnaam>.Empty'. Use the new keyword if hiding was intended.

'Contactgegevens.Empty' hides inherited member 'ReadOnlyCollection<Contactgegeven>.Empty'. Use the new keyword if hiding was intended.

'Datum' defines 'Equals' but not 'GetHashCode'

'HoofdactiviteitenVerenigingsloket.Empty' hides inherited member 'ReadOnlyCollection<HoofdactiviteitVerenigingsloket>.Empty'. Use the new keyword if hiding was intended.

'Lidmaatschappen.Empty' hides inherited member 'ReadOnlyCollection<Lidmaatschap>.Empty'. Use the new keyword if hiding was intended.

'Locaties.Empty' hides inherited member 'ReadOnlyCollection<Locatie>.Empty'. Use the new keyword if hiding was intended.

'Vertegenwoordigers.Empty' hides inherited member 'ReadOnlyCollection<Vertegenwoordiger>.Empty'. Use the new keyword if hiding was intended.

Possible null reference argument for parameter 'arg' in 'TDestination Func<T, TDestination>.Invoke(T arg)'.

Cannot convert null literal to non-nullable reference type.

Possible null reference assignment.

Dereference of a possibly null reference.

Dereference of a possibly null reference.

Dereference of a possibly null reference.

This async method lacks 'await' operators and will run synchronously. Consider using the 'await' operator to await non-blocking API calls, or 'await Task.Run(...)' to do CPU-bound work on a background thread.

'JsonNetSerializer.Customize(Action<JsonSerializer>)' is obsolete: 'Use Configure(Action<JsonSerializerSettings> configure) instead. This overload will be removed in the next major release.'

Dereference of a possibly null reference.

Dereference of a possibly null reference.