[BUG][Kotlin/okhttp-gson] wrong handling of empty response #13718

[zoltanwork]

We use a legacy REST server that returns a non-empty response even if it the response type is Unit. In this case the following exception is thrown: java.lang.IllegalArgumentException: Platform class kotlin.Unit requires explicit JsonAdapter to be registered at com.squareup.moshi.ClassJsonAdapter$1.create(ClassJsonAdapter.java:76) at com.squareup.moshi.Moshi.adapter(Moshi.java:146) at com.squareup.moshi.Moshi.adapter(Moshi.java:106) at com.squareup.moshi.Moshi.adapter(Moshi.java:75) at com.squareup.moshi._MoshiKotlinExtensionsKt.adapter(-MoshiKotlinExtensions.kt:40) ...

I checked another generator (Java/apache-httpclient) to see how it handles this case. There the Java class of the expected result is checked and the code doesn't call the JSON deserializer if no response is expected.

[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]

can you please follow step 3 in the PR checklist to update the samples so that the CI can verify the change?

cc @jimschubert (2017/09) ❤️, @dr4ke616 (2018/08) @karismann (2019/03) @Zomzog (2019/04) @andrewemery (2019/10) @4brunu (2019/11) @yutaka0m (2020/03)

[wing328]

We use a legacy REST server that returns a non-empty response even if it the response type is Unit.

maybe better to update the spec to document the response as non-empty (e.g. string)

you can use customized template as a workaround for your special use case.