[Kotlin] Fix explicitApi/nonPublicApi/generateOneOfAnyOfWrappers generation for kotlinx_serialization

[yzaoui]

There are currently issues with the explicitApi, nonPublicApi, and generateOneOfAnyOfWrappers options when used together with kotlinx_serialization

1. explicitApi + generateOneOfAnyOfWrappers: This generates a wrapper which is missing the public keyword inside of the value class' val value property, which makes the library fail to compile when explicitApi() is enabled in the library since the property doesn't have an explicit public
2. nonPublicApi + generateOneOfAnyOfWrappers: I haven't run into this myself, but while fixing the above I noticed that the template attempts to insert internal in the subclass of the internal interface, but Kotlin doesn't allow this, so it generates invalid code

This also fixes the infrastructure.* classes not generating valid code for explicitApi.

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@karismann @Zomzog @andrewemery @4brunu @stefankoppier @e5l @dennisameling @wing328

---

Summary by cubic

Fixes Kotlin kotlinx_serialization codegen for explicitApi and nonPublicApi. Corrects wrapper visibility and adds missing explicit public/return types in infrastructure so projects compile cleanly.

• Bug Fixes
  • For explicitApi + generateOneOfAnyOfWrappers: make the wrapper value class and its val value explicitly public.
  • For nonPublicApi + generateOneOfAnyOfWrappers: stop marking the nested value class as internal; only the constructor value is internal.
  • For explicitApi templates: add : Unit to BigDecimalAdapter.serialize; expose public kotlinxSerializationAdapters, kotlinxSerializationJson, and their config lambdas (when not nonPublicApi).

^{Written for commit 4a2e32a. Summary will update on new commits. Review in cubic}

[yzaoui]

{{#nonPublicApi}}internal {{/nonPublicApi}}{{^nonPublicApi}}{{#explicitApi}}public {{/explicitApi}}{{/nonPublicApi}}

becomes

{{#explicitApi}}public {{/explicitApi}}

because if nonPublicApi is true, this is an internal interface, which can never have an internal subclass. This subclass is thus effectively always public

[cubic-dev-ai]

No issues found across 3 files

_{Re-trigger cubic}

[yzaoui]

The second change is

val value

becoming

{{#nonPublicApi}}internal {{/nonPublicApi}}{{^nonPublicApi}}{{#explicitApi}}public {{/explicitApi}}{{/nonPublicApi}}val value

Adding the missing public in explicit API mode, and adding the missing internal in non-public mode

[wing328]

Thanks for the PR.

I tested with ./bin/configs/kotlin-oneOf-anyOf-kotlinx-serialization.yaml

After setting just nonPublicApi: true, the output compiles without issues.

But when setting explicitApi: true, the output won't compile:

> Task :compileKotlin FAILED
w: Argument -Xopt-in is deprecated. Please use -opt-in instead
e: file:///C:/Users/User/code/openapi-generator/samples/client/others/kotlin-oneOf-anyOf-kotlinx-serialization/src/main/kotlin/org/openapitools/client/infrastructure/BigDecimalAdapter.kt:14:18 Return type must be specified in explicit API mode.
e: file:///C:/Users/User/code/openapi-generator/samples/client/others/kotlin-oneOf-anyOf-kotlinx-serialization/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt:23:5 Visibility must be specified in explicit API mode.
e: file:///C:/Users/User/code/openapi-generator/samples/client/others/kotlin-oneOf-anyOf-kotlinx-serialization/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt:43:5 Visibility must be specified in explicit API mode.
e: file:///C:/Users/User/code/openapi-generator/samples/client/others/kotlin-oneOf-anyOf-kotlinx-serialization/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt:54:5 Visibility must be specified in explicit API mode.
e: file:///C:/Users/User/code/openapi-generator/samples/client/others/kotlin-oneOf-anyOf-kotlinx-serialization/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt:66:5 Visibility must be specified in explicit API mode.

Does it compile fine in your environment?

[yzaoui]

Thanks for the PR.

I tested with ./bin/configs/kotlin-oneOf-anyOf-kotlinx-serialization.yaml

After setting just nonPublicApi: true, the output compiles without issues.

But when setting explicitApi: true, the output won't compile:

> Task :compileKotlin FAILED
w: Argument -Xopt-in is deprecated. Please use -opt-in instead
e: file:///C:/Users/User/code/openapi-generator/samples/client/others/kotlin-oneOf-anyOf-kotlinx-serialization/src/main/kotlin/org/openapitools/client/infrastructure/BigDecimalAdapter.kt:14:18 Return type must be specified in explicit API mode.
e: file:///C:/Users/User/code/openapi-generator/samples/client/others/kotlin-oneOf-anyOf-kotlinx-serialization/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt:23:5 Visibility must be specified in explicit API mode.
e: file:///C:/Users/User/code/openapi-generator/samples/client/others/kotlin-oneOf-anyOf-kotlinx-serialization/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt:43:5 Visibility must be specified in explicit API mode.
e: file:///C:/Users/User/code/openapi-generator/samples/client/others/kotlin-oneOf-anyOf-kotlinx-serialization/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt:54:5 Visibility must be specified in explicit API mode.
e: file:///C:/Users/User/code/openapi-generator/samples/client/others/kotlin-oneOf-anyOf-kotlinx-serialization/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt:66:5 Visibility must be specified in explicit API mode.

Does it compile fine in your environment?

Ahh I had only tested the generated apis & models for my project since that's all I needed, it looks like these infrastructure classes never worked properly with explicitApi.

Fixed in 4a2e32a!

[cubic-dev-ai]

No issues found across 5 files

_{Re-trigger cubic}

[wing328]

tested explicitApi and nonPublicApi separately and the output compiles without any issue.

will add some tests in CI to cover this issue after merging this PR

[wing328]

update: merged #23864 to add more tests