Fix apiVersion clientDefaultValue missing for multi-service operation groups

[Copilot]

When an operation group contains operations from different services, the clientDefaultValue for apiVersion parameters was incorrectly undefined for all operations. Each operation should get its default from its own service's api version.

Changes

• internal-utils.ts: Added findServiceForOperation helper and modified updateWithApiVersionInformation to accept an optional operation parameter
• types.ts: Pass operation to updateWithApiVersionInformation call site
• structure.test.ts: Added assertions verifying operation-level api version defaults in multi-service scenarios

Before/After

// Multi-service operation group with operations from ServiceA (av1, av2) and ServiceB (bv1, bv2)

// Before: Both operations had undefined clientDefaultValue
aTestMethod.operation.parameters[0].clientDefaultValue // undefined
bTestMethod.operation.parameters[0].clientDefaultValue // undefined

// After: Each operation gets its service's latest version
aTestMethod.operation.parameters[0].clientDefaultValue // "av2"
bTestMethod.operation.parameters[0].clientDefaultValue // "bv2"

Note: Client-level apiVersion parameters for multi-service clients remain undefined by design since there's no single default across services.

Original prompt

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This section details on the original issue you should resolve

<issue_title>[Bug]: ApiVersion param clientDefaultValue is missing if an operation group contain operations from different services</issue_title>
<issue_description>### Describe the bug

This is specific for multiple services in one client scenario.
When an operation group mixes operations from different services, the clientDefaultValue of the apiVersion parameter of all its operations are missing.

Reproduction

This is the related test typespec: https://github.com/Azure/autorest.typescript/tree/main/packages/typespec-test/test/compute/spec
sdkPackage:

Checklist

• Follow our Code of Conduct
• Check that this issue is about the Azure libraries for typespec. For bug in the typespec language or core libraries file it in the TypeSpec repo
• Check that there isn't already an issue that request the same bug to avoid creating a duplicate.
• The provided reproduction is a minimal reproducible example of the bug.</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes [Bug]: ApiVersion param clientDefaultValue is missing if an operation group contain operations from different services #3886

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commit: 470183f

[azure-sdk]

All changed packages have been documented.

• ✅ @azure-tools/typespec-client-generator-core

Show changes

@azure-tools/typespec-client-generator-core - fix ✏️

Fixed apiVersion parameter clientDefaultValue missing when an operation group contains operations from different services.

[azure-sdk]

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