Make CredentialDescription AOT-compatible via C# 14 extension properties (v11.0.0)

[Copilot]

AOT/NativeAOT Compatibility for CredentialDescription (.NET 10+) - v11.0.0

✅ Implementation Complete - All Feedback Addressed

• Version bumped to 11.0.0
• Changelog with troubleshooting guidance
• C# 14 extension properties
• AOT test project added
• CI pipeline with AOT tests
• Methods changed to protected internal
• Copy constructor simplified
• CA1024 pragma added
• Documentation refined - Clarifies C# 14 available on all TFMs, used on .NET 10+ by library design

📊 Implementation

Core Changes:

• CredentialDescription.cs - Conditional compilation, protected internal methods
• CredentialDescriptionExtensions.cs - C# 14 extension properties (.NET 10+ by design)
• Directory.Build.props - LangVersion 14, Version 11.0.0
• PublicAPI files - Updated for net10.0
• changelog.md - Breaking change documentation with troubleshooting
• Microsoft.Identity.Abstractions.AotTests - AOT validation project
• .github/workflows/dotnetcore.yml - Automated AOT testing

🎯 Design Decisions

Extension Properties Implementation:

• C# 14 extension properties work on any target framework (language feature)
• This library exposes them only on .NET 10+ by design
• Reason: Avoid binary breaking changes on older frameworks
• Older TFMs keep regular properties (backward compatible)

Why Protected Internal:

• Derived classes in other assemblies need access to methods
• Cannot use base.Certificate with extension properties
• Enables inheritance scenarios (e.g., CertificateDescription in Microsoft.Identity.Web)

Why CA1024 Pragma:

• Get* methods intentionally not properties
• Support extension property pattern
• Prevents analyzer warnings

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Status: Ready for merge
Version: 11.0.0 | C# Version: 14+
TFMs: net10.0, net9.0, net8.0, net462, netstandard2.0/2.1

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[jmprieur]

@copilot this is a great start. I left some comments.
Also we need to increase the major version as this is a public API binary breaking change (even if this should be source compatible)

[Copilot]

@copilot this is a great start. I left some comments.
Also we need to increase the major version as this is a public API binary breaking change (even if this should be source compatible)

Addressed all feedback in commit 3b6093a:

• Reverted NuGet.config changes (was only needed for local network issues)
• Changed LangVersion from preview to 14 (C# 14 is released)
• Updated all documentation to reference C# 14 instead of C# 15
• Explained the performance optimization in Id property

Regarding the major version: the changelog shows we're already at version 10.0.0, which is a major bump from 9.x. The changes are in the 10.0.0 section. Should we bump to 11.0.0 instead?

[bgavrilMS]

Approved with comments.

[jmprieur]

@copilot, please check the new comments where i tagged you

[jmprieur]

@copilot : another round of comments to address, and I think we'll be good