fix(kotlin-client): use enum value in query (#18236)

[Tooa]

This commit fixes an issue where enums are used as a value in either path or query params due to relying on string casting. With this change, enum values are requested by using .value instead.

I also used kotlin string interpolation to address one of the AI review feedback comments. The change is in line with the multiplatform implementation.

Scope: This MR just fixes issues with scalar enums.

Related to #18236.

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Summary by cubic

Fix Kotlin client query parameter handling to use enum.value and Kotlin string interpolation in jvm-spring-restclient and jvm-spring-webclient templates. Also fixes a broken string interpolation case and regenerates Kotlin samples (echo and petstore) to ensure correct URL serialization and prevent invalid requests.

^{Written for commit 126ac09. Summary will update on new commits.}

[cubic-dev-ai]

2 issues found across 2 files

Prompt for AI agents (all issues)

Check if these issues are valid — if so, understand the root cause of each and fix them.


<file name="modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-spring-webclient/api.mustache">

<violation number="1" location="modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-spring-webclient/api.mustache:106">
P2: Enum query parameters now pass raw `.value` into `listOf(...)`, which breaks the `List<String>` type when enum values are non-String (e.g., Int). Generated clients will not compile for such enums.</violation>
</file>

<file name="modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-spring-restclient/api.mustache">

<violation number="1" location="modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-spring-restclient/api.mustache:104">
P2: Container enum query parameters still serialize via toMultiValue’s default toString() converter, so list/array enums will continue to send enum names instead of their .value. The fix only handles scalar enums and leaves container enums unchanged.</violation>
</file>

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[cubic-dev-ai]

2 issues found across 2 files (changes from recent commits).

Prompt for AI agents (all issues)

Check if these issues are valid — if so, understand the root cause of each and fix them.


<file name="modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-spring-restclient/api.mustache">

<violation number="1" location="modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-spring-restclient/api.mustache:104">
P2: Enum collections in query parameters are still serialized using toString via toMultiValue, so enum arrays/lists send enum names instead of the enum value, inconsistent with scalar enum handling.</violation>
</file>

<file name="modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-spring-webclient/api.mustache">

<violation number="1" location="modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-spring-webclient/api.mustache:106">
P2: List/array enum query params still serialize via toMultiValue’s default `$item` conversion, which uses enum name rather than the enum `value`, causing inconsistent and potentially incorrect query values compared to scalar enums.</violation>
</file>

_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review.}

[Tooa]

I am done from my side for now. Let me know if you want anything changed.

[cubic-dev-ai]

4 issues found across 5 files (changes from recent commits).

Prompt for AI agents (all issues)

Check if these issues are valid — if so, understand the root cause of each and fix them.


<file name="samples/client/echo_api/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/apis/QueryApi.kt">

<violation number="1" location="samples/client/echo_api/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/apis/QueryApi.kt:70">
P2: Malformed Kotlin string template; property access needs braces. This will send "<enum>.value}" instead of the enum value.</violation>

<violation number="2" location="samples/client/echo_api/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/apis/QueryApi.kt:73">
P2: Malformed Kotlin string template; property access needs braces. This will send "<enum>.value}" instead of the enum value.</violation>
</file>

<file name="samples/client/echo_api/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/apis/QueryApi.kt">

<violation number="1" location="samples/client/echo_api/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/apis/QueryApi.kt:74">
P2: Malformed string interpolation appends a literal `.value}` instead of the enum value, producing incorrect query strings.</violation>

<violation number="2" location="samples/client/echo_api/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/apis/QueryApi.kt:77">
P2: Malformed string interpolation appends a literal `.value}` instead of the enum value, producing incorrect query strings.</violation>
</file>

_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review.}

[Tooa]

Can someone have a look? Would love to get this merged.

/cc @karismann @Zomzog @andrewemery @4brunu @yutaka0m @stefankoppier @e5l @dennisameling @wing328