[BUG][Kotlin] Data class generated with unneded { } and backspaces

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

I inherited a work project using Swagger and OpenAPI. When updating the classes with openapi-generator-cli , the DTO data classes have unwanted / unneeded { } at the end of the file:

data class MyModelRequestDto (
    ...
) {


}

openapi-generator version

I'm using openapi-generator-cli-7.9.0 (previous one was 7.4.0).

OpenAPI declaration file content or url

This is the script the previous developer used to launch the generator:

#!/bin/sh
echo "Start generation API for mobile"

java -jar openapi-generator-cli-7.9.0.jar generate \
 -i https://my.work/swagger/v7/swagger.json \
 -g kotlin \
 --package-name com.work.services.mobile \
 --library jvm-retrofit2 \
 --additional-properties=additionalModelTypeAnnotations=@kotlinx.serialization.Serializable \
 --additional-properties=dateLibrary=string \
 --additional-properties=useCoroutines=true \
 --additional-properties=omitGradleWrapper=true \
 --type-mappings=java.util.UUID=String \
 --language-specific-primitives=Int \
 --type-mappings=integer=Int \
 --language-specific-primitives=String \
 --type-mappings=string=String \
 --language-specific-primitives=Boolean \
 --type-mappings=boolean=Boolean \
 --additional-properties=groupId=com.work.services \
 --global-property=modelDocs=false \
 --global-property=modelTests=false \
 --global-property=apiDocs=false \
 --global-property=apiTests=false \
 -o ../mobile-api/

echo "Generation API for mobile ended"

Generation Details

Nothing to declare (I suppose).

Steps to reproduce

Update generator from a previous version.
Launch the script .sh above.
See issues on data classes.

Related issues/PRs

Didn't find any similar issues by searching with "kotlin", "data class", "{" keywords.

Suggest a fix

Start with the provided shell script and compare the Kotlin model output from openapi-generator-cli 7.9.0 with 7.4.0, using the referenced Swagger JSON input if available. Trace the Kotlin model-generation entry point responsible for the data class declaration. Done means generated data classes no longer contain the unwanted empty braces or backspaces, with the behavior verified against a minimal reproducible input.