chore(main): release 3.9.0

[release-please-token-provider]

🤖 I have created a release beep boop

3.9.0 (2026-07-14)

Features

• adds support for anchor and id external resolution (1591007)
• schema: resolve bare $dynamicRef via $dynamicAnchor index (#2913) (eacc2fc)

Bug Fixes

• adds explicit error message for invalid json pointers (63fc55d)
• adds explicit error message for invalid json pointers (bc93efe)
• default mapping is not being serialized with the correct shape (fe4a25f)
• differentiate unset value from null value in OpenApiSchema.Const (#2936) (07b525f)
• handle nullability more accurately during serialization for 3.0/2.0 (#2933) (0ace243)
• validate required properties of security scheme before serialization (#2952) (f31b192)

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[github-code-quality]

Code Coverage Overview

Languages: C#

C# / code-coverage/dotnet

The overall coverage remains at 89%, unchanged from the main branch.

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_{Updated July 14, 2026 18:50 UTC
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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud