fix(kotlin): set isVoid to true for Unit datatypes

[knuterikl]

Sets the isVoid to true for CodegenResponses and CodegenOperation when the type is Unit (java void) so that isVoid can be used in mustache templates.

Unit
The type with only one value: the Unit object. This type corresponds to the void type in Java.
https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/

PR checklist

• Read the contribution guidelines.
• Pull Request title clearly describes the work in the pull request and Pull Request description provides details about how to validate the work. Missing information here may result in delayed response from the community.
• Run the following to build the project and update samples:

  ./mvnw clean package || exit
  ./bin/generate-samples.sh ./bin/configs/*.yaml || exit
  ./bin/utils/export_docs_generators.sh || exit
  

  (For Windows users, please run the script in WSL)
  Commit all changed files.
  This is important, as CI jobs will verify all generator outputs of your HEAD commit as it would merge with master.
  These must match the expectations made by your contribution.
  You may regenerate an individual generator by passing the relevant config(s) as an argument to the script, for example ./bin/generate-samples.sh bin/configs/java*.
  IMPORTANT: Do NOT purge/delete any folders/files (e.g. tests) when regenerating the samples as manually written tests may be removed.
• File the PR against the correct branch: master (upcoming 7.x.0 minor release - breaking changes with fallbacks), 8.0.x (breaking changes without fallbacks)
• If your PR solves a reported issue, reference it using GitHub's linking syntax (e.g., having "fixes #123" present in the PR description)
• If your PR is targeting a particular programming language, @mention the technical committee members, so they are more likely to review the pull request.

@dr4ke616 (2018/08) @karismann (2019/03) @Zomzog (2019/04) @andrewemery (2019/10) @4brunu (2019/11) @yutaka0m (2020/03) @stefankoppier (2022/06) @e5l (2024/10)

[wing328]

thanks for the PR

Sets the isVoid to true for CodegenResponses and CodegenProperty when the type is Unit (java void)

for response, i see the use cases CodegenResponse with isVoid set to true

but for CodegenProperty, what's the use case the type is Unit (java void)?

what type does it correspond to in OpenAPI specification?

[knuterikl]

thanks for the PR

Sets the isVoid to true for CodegenResponses and CodegenProperty when the type is Unit (java void)

for response, i see the use cases CodegenResponse with isVoid set to true

but for CodegenProperty, what's the use case the type is Unit (java void)?

what type does it correspond to in OpenAPI specification?

You are absolutely right. I assumed that the interface I was extending also was used for mapping datatypes for CodegenProperty 😅 . The correct statement is that isVoid is set to true for CodegenResponse and CodegenOperation (which I assumed was the same).

[wing328]

ok. thanks for the explanation

let's give it a try