HttpResponse.ContentType is marked as String but is null sometimes

[Patrick8639]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

In some cases, the value of HttpResponse.ContentType can be null, but the property is defined as String and not String?.
The problem is that, if we test whether ContentType is null, Intellisense complains that the value cannot be null.

Expected Behavior

Either one:

• Define the property value as String?.
• Define a default non-null value is the constructor(s).

Steps To Reproduce

This is the minimal code to show the problem.

Implement an endpoint to catch OPTIONS request:

public static class OptionsRequest
{
  private static Task ProcessAsync (
    HttpContext context
  )
  {
    var Response = context.Response;
  }
}

Register the endpoint:

app.UseEndpoints (
    endpoints =>
    {
      endpoints.MapMethods ("/{*all}", new String [] { "OPTIONS" }, ProcessAsync)
    }
);

When the OptionsRequest.ProcessAsync method is called, Response .ContentType is null.

Exceptions (if any)

No response

.NET Version

6.0.6

Anything else?

ASP.NET Core 6.0.6
VS pro 17.2.4

dotnet --info:

.NET SDK (reflecting any global.json):
 Version:   6.0.301
 Commit:    43f9b18481

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.22000
 OS Platform: Windows
 RID:         win10-x64
 Base Path:   C:\Program Files\dotnet\sdk\6.0.301\

Host (useful for support):
  Version: 6.0.6
  Commit:  7cca709db2

.NET SDKs installed:
  5.0.301 [C:\Program Files\dotnet\sdk]
  5.0.409 [C:\Program Files\dotnet\sdk]
  6.0.100-rc.2.21505.57 [C:\Program Files\dotnet\sdk]
  6.0.301 [C:\Program Files\dotnet\sdk]

.NET runtimes installed:
  Microsoft.AspNetCore.App 3.1.26 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 5.0.7 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 5.0.9 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 6.0.1 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 6.0.6 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 3.1.22 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.1.26 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 5.0.7 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 5.0.9 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 6.0.1 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 6.0.3 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 6.0.6 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.WindowsDesktop.App 3.1.22 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 3.1.26 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 6.0.3 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 6.0.6 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

To install additional .NET runtimes or SDKs:
  https://aka.ms/dotnet-download

[campersau]

I guess this is already fixed in .NET 7 #35547

aspnetcore/src/Http/Http.Abstractions/src/HttpResponse.cs

Line 62 in 8897c29

public abstract string? ContentType { get; set; }

[Patrick8639]

@campersau
Yes, but the problem is here in .NET 6...

[BrennanConroy]

Yes, but the problem is here in .NET 6...

It's unfortunate, but we can't make API changes in a patch. You'll either need to use .NET 7 or suppress the warning.

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