[http-client-csharp] emitter support for @clientDefaultValue on model properties

[JoshLove-msft]

The Azure C# emitter does not currently apply client-side default values for model properties marked with the legacy @clientDefaultValue decorator. The Spector test Azure_ClientGenerator_Core_ClientDefaultValue_PutModelProperty (in azure-http-specs) constructs new ModelWithDefaultValues("test") and expects timeout=30, tier="standard", retry=true to be auto-populated and serialized, but only name is sent.rnrnThe test is currently [Ignore]-d in ClientDefaultValueTests.cs pending emitter support.

[github-actions]

🎯 Issue Triage

The C# HTTP client emitter lacks support for applying client-side default values to model properties decorated with @clientDefaultValue. The related Spector test (Azure_ClientGenerator_Core_ClientDefaultValue_PutModelProperty) is currently ignored pending emitter implementation.

Category: Feature Request

Area: emitter:client:csharp

🔍 Analysis

• The @clientDefaultValue decorator is a legacy Azure client generator core decorator that instructs client emitters to pre-populate model properties with default values.
• The C# emitter currently does not generate code to apply these defaults, so constructed model instances only include explicitly set properties (e.g., name), omitting timeout=30, tier="standard", and retry=true.
• The Spector test ClientDefaultValueTests.cs is [Ignore]-d, providing a ready-made acceptance test once the emitter emits the default-value logic.
• Implementation likely requires reading the @clientDefaultValue metadata in the C# emitter and emitting property initializers or constructor assignments for affected properties.

📝 Suggested next steps

• Implement @clientDefaultValue handling in the C# emitter to generate default property values for model properties.
• Remove the [Ignore] attribute from ClientDefaultValueTests.cs and verify the Spector test passes.

Generated by Agentic Triage