Omit null OpenAPI response descriptions

[Copilot]

Pull Request

Description

OpenAPI response descriptions must be strings when present. Responses with no description were serialized as "description": null, which Swagger Editor rejects.

"200": {}

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Other (please describe):

Related Issue(s)

Changes Made

• Serialization
  • Omit description from OpenApiResponse when Description is null.
• Coverage
  • Added response serialization coverage for OpenAPI 2.0, 3.0, 3.1, and 3.2.
• Expectations
  • Updated affected operation serialization baselines.

Testing

• Unit tests added/updated
• Integration tests added/updated
• Manual testing performed
• All existing tests pass

Checklist

• My code follows the code style of this project
• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

Versions applicability

• My change applies to the version 1.X of the library, if so PR link:
• My change applies to the version 2.X of the library, if so PR link:
• My change applies to the version 3.X of the library, if so PR link:
• I have evaluated the applicability of my change against the other versions above.

Additional Notes

None.

• Fixes Description in Response cannot be null #3069

[github-code-quality]

Code Coverage Overview

Languages: C#

C# / code-coverage/dotnet

The overall line coverage in commit aadddd7 in the copilot/fix-descript... branch remains at 32%, unchanged from commit 1dae1ff in the main branch.

Show a line coverage summary of the most impacted files.

File	main 1dae1ff	copilot/fix-descript... aadddd7	+/-
_/src/Moq/Interception/Mock.cs	0%	11%	+11%
_/src/Moq/MethodCall.cs	0%	18%	+18%
_/src/Moq/Extensions.cs	0%	18%	+18%
_/src/Moq/Prote...rotectedMock.cs	0%	19%	+19%
_/src/Moq/Inter...ProxyFactory.cs	0%	20%	+20%
_/src/Moq/Mock`1.cs	0%	26%	+26%
_/src/Moq/MethodExpectation.cs	0%	40%	+40%
_/src/Humanizer...s/Vocabulary.cs	0%	68%	+68%
_/src/Moq/MatcherObserver.cs	0%	74%	+74%
_/src/Humanizer...Vocabularies.cs	0%	100%	+100%

[Copilot]

🟢 Approval recommended

The fix is covered by cross-version tests with no unresolved issues.

Pull request overview

This pull request fixes OpenAPI response serialization by omitting null description fields.

Changes:

• Omits null descriptions across OpenAPI 2.0–3.2.
• Adds cross-version serialization coverage.
• Updates affected serialization baselines.

File summaries

File	Description
test/Microsoft.OpenApi.Tests/Models/OpenApiResponseTests.cs	Updates empty-response expectations.
test/Microsoft.OpenApi.Tests/Models/OpenApiOperationTests.cs	Updates operation serialization baselines.
test/Microsoft.OpenApi.Tests/Mocks/OpenApiResponseSerializationTests.cs	Adds cross-version coverage.
src/Microsoft.OpenApi/Models/OpenApiResponse.cs	Omits null descriptions during serialization.

Review details

• Files reviewed: 4/4 changed files
• Comments generated: 0
• Review effort level: Lite

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud