Incorrect nullability on IApiRequestFormatMetadataProvider.GetSupport…

[codingwithstephen]

Incorrect nullability on IApiRequestFormatMetadataProvider.GetSupportedContentTypes #62405

Fix incorrect nullability in GetSupportedContentTypes

Summary of the changes:
Corrected the nullability annotations for the GetSupportedContentTypes method in the IApiRequestFormatMetadataProvider interface to match the expected behavior.

Description

This PR fixes the nullability specification on the GetSupportedContentTypes method to ensure correct usage and compatibility with nullable reference types.

Due to the requirement of a specific .NET SDK version (10.0.100-preview.7.25322.101) pinned in global.json, I have not been able to build the solution or run existing tests. Additionally, after searching the codebase, I could not find any existing unit tests covering this particular feature or method.

Fixes #62405

[martincostello]

This guide explains how to build the code locally: https://github.com/dotnet/aspnetcore/blob/main/docs/BuildFromSource.md

There are scripts to download the required SDK version and make it available for use in your IDE of choice.

[codingwithstephen]

@dotnet-policy-service agree

[codingwithstephen]

@martincostello I am getting the build errors below. But I had to change these files in order for the tests to pass. What should I do here?

❌Detected modification to baseline API files. PublicAPI.Shipped.txt files should only be updated after a major release, and PublicAPI.Unshipped.txt files should not be updated in release branches. See /docs/APIBaselines.md for more information.
❌Modified API baseline files:
❌src/Mvc/Mvc.Core/src/PublicAPI.Shipped.txt

[martincostello]

Sorry, I don't know the answer to that specific question for this repo.

[captainsafia]

@codingwithstephen Thanks for opening this PR!

We use the PublicAPI analyzers to manage API versions in our application. The analyzer is complaining because the nullability changes should be applied in the PublicApi.Unshipped.txt file in the project directory.

Are you using VS or VS Code? There should be a codefixer offered to make this change? If not, you can try implementing it manually by creating a new PublicApi.Unshipped.txt file in this directory and adding the type signature with nullability and removing the type signature without it. Something like this:

*REMOVED*Microsoft.AspNetCore.Mvc.ApiExplorer.IApiRequestFormatMetadataProvider.GetSupportedContentTypes(string! contentType, System.Type! objectType) -> System.Collections.Generic.IReadOnlyList<string!>?
Microsoft.AspNetCore.Mvc.ApiExplorer.IApiRequestFormatMetadataProvider.GetSupportedContentTypes(string? contentType, System.Type! objectType) -> System.Collections.Generic.IReadOnlyList<string!>?