[kotlin] Fix #22049 by removing multiplatform-check that added another set of () when isMap also was true

[dmh002-politiet]

fixes #22049

data_mustache had a lot of logic to add () to the final file. Added a test case and proper yaml that helps reproduce and catch the issue.

Given this targets Kotlin and multiplatform, i am tagging @jimschubert and @andrewemery as instructed

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Summary by cubic

Fixes #22049 by removing a multiplatform-only () call in the Kotlin client template that added extra parentheses for map types, ensuring free-form objects (additionalProperties: {}) generate as HashMap<String, Any>() in the multiplatform library. Adds a test and sample OpenAPI spec that generate FreeFormObject.kt and assert the expected map initialization.

^{Written for commit c391ae4. Summary will update on new commits.}

[dmh002-politiet]

I am hesitant to commit the generated files after running the checklists build command, as there seems to be 364 unrelated files that has changes. Some advice on what to do would be appreciated.

[cubic-dev-ai]

1 issue found across 3 files

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="modules/openapi-generator/src/main/resources/kotlin-client/data_class.mustache">

<violation number="1" location="modules/openapi-generator/src/main/resources/kotlin-client/data_class.mustache:111">
P1: Regression risk: parent class inheritance may be generated without required `()` in multiplatform/kotlinx mode, producing invalid Kotlin (`: Parent` instead of `: Parent()`).</violation>
</file>

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[cubic-dev-ai]

P1: Regression risk: parent class inheritance may be generated without required () in multiplatform/kotlinx mode, producing invalid Kotlin (: Parent instead of : Parent()).

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At modules/openapi-generator/src/main/resources/kotlin-client/data_class.mustache, line 111:

<comment>Regression risk: parent class inheritance may be generated without required `()` in multiplatform/kotlinx mode, producing invalid Kotlin (`: Parent` instead of `: Parent()`).</comment>

<file context>
@@ -108,7 +108,7 @@ import {{packageName}}.infrastructure.ITransformForStorage
 
 {{/allVars}}
-){{/discriminator}}{{#parent}}{{^serializableModel}}{{^parcelizeModels}} : {{{parent}}}{{#isMap}}(){{/isMap}}{{#kotlinx_serialization}}(){{/kotlinx_serialization}}{{#multiplatform}}(){{/multiplatform}}{{#isArray}}(){{/isArray}}{{/parcelizeModels}}{{/serializableModel}}{{/parent}}{{#parent}}{{#serializableModel}}{{^parcelizeModels}} : {{{parent}}}{{#isMap}}(){{/isMap}}{{#isArray}}(){{/isArray}}, Serializable{{/parcelizeModels}}{{/serializableModel}}{{/parent}}{{#parent}}{{^serializableModel}}{{#parcelizeModels}} : {{{parent}}}{{#isMap}}(){{/isMap}}{{#isArray}}(){{/isArray}}, Parcelable{{/parcelizeModels}}{{/serializableModel}}{{/parent}}{{#parent}}{{#serializableModel}}{{#parcelizeModels}} : {{{parent}}}{{#isMap}}(){{/isMap}}{{#isArray}}(){{/isArray}}, Serializable, Parcelable{{/parcelizeModels}}{{/serializableModel}}{{/parent}}{{^parent}}{{#serializableModel}}{{^parcelizeModels}} : Serializable{{/parcelizeModels}}{{/serializableModel}}{{/parent}}{{^parent}}{{^serializableModel}}{{#parcelizeModels}} : Parcelable{{/parcelizeModels}}{{/serializableModel}}{{/parent}}{{^parent}}{{#serializableModel}}{{#parcelizeModels}} : Serializable, Parcelable{{/parcelizeModels}}{{/serializableModel}}{{/parent}}{{#generateRoomModels}}{{#parent}}, {{/parent}}{{^discriminator}}{{^parent}}:{{/parent}} ITransformForStorage<{{classname}}RoomModel>{{/discriminator}}{{/generateRoomModels}}{{#vendorExtensions.x-has-data-class-body}} {
+){{/discriminator}}{{#parent}}{{^serializableModel}}{{^parcelizeModels}} : {{{parent}}}{{#isMap}}(){{/isMap}}{{#isArray}}(){{/isArray}}{{/parcelizeModels}}{{/serializableModel}}{{/parent}}{{#parent}}{{#serializableModel}}{{^parcelizeModels}} : {{{parent}}}{{#isMap}}(){{/isMap}}{{#isArray}}(){{/isArray}}, Serializable{{/parcelizeModels}}{{/serializableModel}}{{/parent}}{{#parent}}{{^serializableModel}}{{#parcelizeModels}} : {{{parent}}}{{#isMap}}(){{/isMap}}{{#isArray}}(){{/isArray}}, Parcelable{{/parcelizeModels}}{{/serializableModel}}{{/parent}}{{#parent}}{{#serializableModel}}{{#parcelizeModels}} : {{{parent}}}{{#isMap}}(){{/isMap}}{{#isArray}}(){{/isArray}}, Serializable, Parcelable{{/parcelizeModels}}{{/serializableModel}}{{/parent}}{{^parent}}{{#serializableModel}}{{^parcelizeModels}} : Serializable{{/parcelizeModels}}{{/serializableModel}}{{/parent}}{{^parent}}{{^serializableModel}}{{#parcelizeModels}} : Parcelable{{/parcelizeModels}}{{/serializableModel}}{{/parent}}{{^parent}}{{#serializableModel}}{{#parcelizeModels}} : Serializable, Parcelable{{/parcelizeModels}}{{/serializableModel}}{{/parent}}{{#generateRoomModels}}{{#parent}}, {{/parent}}{{^discriminator}}{{^parent}}:{{/parent}} ITransformForStorage<{{classname}}RoomModel>{{/discriminator}}{{/generateRoomModels}}{{#vendorExtensions.x-has-data-class-body}} {
 {{/vendorExtensions.x-has-data-class-body}}
 {{#generateRoomModels}}
</file context>