Fix Retrofit template with Jackson for Kotlin

[yonatankarp]

To fix #8147

This commit amends the ApiClient template for Retrofit. It fixes a bug where the Retrofit client uses Jackson as the serialization library.

Until now, the ApiClient could not be compiled when using the Jackson library (default in SpringBoot applications), as the constructor of the class had the following parameter:

private val serializerBuilder: Builder = Serializer.Builder,

You can see it more clearly here:

After the fix the outcome of this line would be:

private val serializerBuilder: ObjectMapper = Serializer.jacksonObjectMapper,

The configuration that was used for the test is as follows:

config = mapOf(
    "dateLibrary" to "java8",
    "interfaceOnly" to "true",
    "implicitHeaders" to "true",
    "hideGenerationTimestamp" to "true",
    "useTags" to "true",
    "documentationProvider" to "none",
    "serializationLibrary" to "jackson",
    "useCoroutines" to "true",
    "library" to "jvm-retrofit2"
)

Commits:

1. The bug fix itself
2. Adding code sample for CI comparison
3. Update existing samples with the new change.

All commits would be squashed into a single commit when this PR is approved, and are separated only for easier review process.

---

The change done in the commit is to ensure that in the case of Jackson, the right property of the Serializer class is assigned

validation of this change was by running the generator and ensuring that code the generated code passed compilation.

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[yonatankarp]

@jimschubert could you please have a look? Noticed this bug at work yesterday. We've fixed it locally by altering the templates, but I think that it's better to fix it on the generator level.

[yonatankarp]

@jimschubert after rebasing again on master all broken CI's have passed. can you please review this small fix? 🙏

[wing328]

@yonatankarp thanks for the PR. Can you please PM me via Slack to discuss this further?

https://join.slack.com/t/openapi-generator/shared_invite/zt-12jxxd7p2-XUeQM~4pzsU9x~eGLQqX2g

[wing328]

I did a test locally but got the following errors:

➜  kotlin-jvm-jackson git:(fix_retrofit_generator_with_jackson) ✗ gradle build
Starting a Gradle Daemon (subsequent builds will be faster)

> Task :compileKotlin
e: /Users/williamcheng/gitclone/yonatankarp_fix_retrofit_generator_with_jackson/samples/client/petstore/kotlin-jvm-jackson/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt: (60, 28): Unresolved reference: Builder
e: /Users/williamcheng/gitclone/yonatankarp_fix_retrofit_generator_with_jackson/samples/client/petstore/kotlin-jvm-jackson/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt: (60, 49): Unresolved reference: Builder
e: /Users/williamcheng/gitclone/yonatankarp_fix_retrofit_generator_with_jackson/samples/client/petstore/kotlin-jvm-jackson/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt: (75, 28): Unresolved reference: Builder
e: /Users/williamcheng/gitclone/yonatankarp_fix_retrofit_generator_with_jackson/samples/client/petstore/kotlin-jvm-jackson/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt: (75, 49): Unresolved reference: Builder

> Task :compileKotlin FAILED

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':compileKotlin'.
> A failure occurred while executing org.jetbrains.kotlin.compilerRunner.GradleCompilerRunnerWithWorkers$GradleKotlinCompilerWorkAction
   > Compilation error. See log for more details

* Try:
> Run with --stacktrace option to get the stack trace.
> Run with --info or --debug option to get more log output.
> Run with --scan to get full insights.
> Get more help at https://help.gradle.org.

Can you please take a look when you've time?

Also update use 3.0 spec instead: modules/openapi-generator/src/test/resources/3_0/petstore.yaml

[wing328]

Please commit the new sample files as well so that github workflow will trigger the build.

[yonatankarp]

There was indeed a but with my fix - my bad! 🤦‍♂️
I have fixed it and updated the sample app and the spec version however seems that GitHub Actions isn't picking the changes yet, and CircleCI still failing after I have rebased on master

[wing328]

please ignore the circleci failure for the time being.

can you please update the samples?

ref: https://github.com/OpenAPITools/openapi-generator/actions/runs/5840007126/job/15839427531?pr=14239

[yonatankarp]

@wing328 I have rebased the branch on master again (seems that previously it was wrongly done as the generator version was 6.3.0-SNAPSHOT on my branch) and also executed the command:

$ bin/generate-samples.sh bin/configs/kotlin-*

Everything should (hopefully) be up-to-date now, and waiting for approval for GitHub to run the pipeline.

Moreover, the PR was split into 3 different commits to ensure easier review process 😄

[wing328]

Thanks for the PR but your commit (as shown in the Commits tab) is not linked to your Github account, which means this PR won't count as your contribution in https://github.com/OpenAPITools/openapi-generator/graphs/contributors.

Let me know if you need help fixing it.

Ref: https://github.com/OpenAPITools/openapi-generator/wiki/FAQ#how-can-i-update-commits-that-are-not-linked-to-my-github-account

[wing328]

https://github.com/OpenAPITools/openapi-generator/actions/runs/5847743068/job/15854622468?pr=14239 failure can be ignored for the time being.

[yonatankarp]

Thanks a lot for noticing that!

I believe that now the commits are linked to your GitHub account.

[wing328]

tests passed: https://github.com/OpenAPITools/openapi-generator/actions/runs/5848309681/job/15860965534?pr=14239