[API Compat] Sealing a class unnoticed

[JanKrivanek]

Context

dotnet/msbuild#10172 intorduced sealing of pre-existing OM classes, while only 2 of the 3 sealed classes were noticed by the API compat scan.

Repro details

• suppression file: https://github.com/dotnet/msbuild/pull/10172/files#diff-6c2861bebb30e66967638b5067f5b31dbb49f09794fd749db5a8f48d68c440a8 (exceptions for BuildRequestData and BuildResult)
• BuildSubmission sealed as part of this change: https://github.com/dotnet/msbuild/pull/10172/files#diff-c3328a495b5bd3db857e885189521b6813dad935fd0f572a80f85a93aa4e32b2R154
• BuildSubmission being public, unsealed in base: https://github.com/dotnet/msbuild/blob/main/src/Build/BackEnd/BuildManager/BuildSubmission.cs#L29

Additional details

• Refactoring introduced a generic unsealed abstract class with the same name: https://github.com/dotnet/msbuild/pull/10172/files#diff-c3328a495b5bd3db857e885189521b6813dad935fd0f572a80f85a93aa4e32b2R23 - so possibly the checking got confused by that?

[dotnet-policy-service]

@dotnet/area-infrastructure-libraries a new issue has been filed in the ApiCompat area, please triage