Api Convention-related types missing from `Microsoft.AspNetCore.Mvc.Core` `2.3.0`

[julealgon]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

As part of a process to upgrade our NET472 applications from AspNetCore 2.2 to the newer 2.3 packages, we started getting build failures when we got to upgrading the Microsoft.AspNetCore.Mvc.Core NuGet from version 2.2.2 to 2.3.0, as multiple types related to API conventions appear to be completely missing from this specific version of the package.

Here is a list of some of the types that are missing:

• ProducesDefaultResponseTypeAttribute
• ApiConventionNameMatchAttribute
• ApiConventionNameMatchBehavior
• ApiConventionTypeMatchBehavior
• ApiConventionTypeAttribute

Since we are using a custom API convention class, this broke our project and we cannot move forward without removing our convention, which I would like to avoid doing.

Expected Behavior

All types from previous versions of the Microsoft.AspNetCore.Mvc.Core package should still be present in the 2.3.0 version, including those related to API conventions.

Steps To Reproduce

https://github.com/julealgon/issueRepros-aspnetcore-missingApiConventionTypes

1. Open the solution, observe compilation fails.
2. Change version of the package in project from 2.3.0 to 2.2.0
3. Observe compilation now succeeds

Exceptions (if any)

No response

.NET Version

NET472

Anything else?

It's not clear to me exactly why these specific types are missing, but I'm currently assuming it must be something related to trimming that removed these types during build.

I actually downloaded the nuget package directly to make sure those types were really not there, and confirmed they are also missing from the documentation XML inside of the package, meaning they were eliminated completely before the final dll was generated somehow.

Upgrading the consuming project makes no difference whatsoever (I tried just to see if it would make a difference, from net472 to net9.0 for example).

The latest version from the AspNetCore.AppRef is working just fine (again, tested by removing the explicit package, and changing to the .Web project SDK).

The only workaround for us at the moment seems to be to completely remove our custom API convention class. Nothing else was affected apparently.

[BrennanConroy]

dotnet/announcements#331
TLDR; 2.2 has been out of support for years and people weren't aware. So we've re-shipped 2.1 as 2.3 so they'll hopefully see a package upgrade which will put them on the supported train. The package upgrade is moving them back to 2.1 so you won't be able to use features that were added in 2.2.

[julealgon]

The package upgrade is moving them back to 2.1 so you won't be able to use features that were added in 2.2.

@BrennanConroy thank you for the clarification... I spent a few hours yesterday trying several different things locally and later I searched for issues here in the repo. At the time, I saw that pinned announcement issue but I completely misinterpreted that to be just a "ASPNET Core 2.3 is here" type of announcement.

Now that you mentioned it again, I properly went through it and now I fully understand what is happening here. It was certainly a very weird decision, but I do get why it was chosen.

I guess we'll have to move straight to .NET 9 on our side for this API.

Apologies for the churn on this one. I should've paid more attention to that pinned item.

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