[BUG][KOTLIN] When generating apis and modals only using retrofit2 api files contain invalid import

Description

When generating code using kotlin generator with options to generate APIs and models files only, and using retrofit2 library, generator generates API files without infrastructure package, but API files contain imports of infrastructure classes which results into an error. In particular this one:

import com.example.api.infrastructure.CollectionFormats.*

openapi-generator version

6.3.0

OpenAPI declaration file content or url

task generateApi(type: GenerateTask) {
generateApi.generatorName = "kotlin"
generateApi.packageName = "com.example.api"
generateApi.inputSpec = "api.json"
generateApi.outputDir = "$rootDir/api"
generateApi.skipValidateSpec = true

generateApi.additionalProperties = [
        useCoroutines: "true",
        library      : "jvm-retrofit2",
        sourceFolder : "src/main/java",
]
generateApi.globalProperties = [
        apiDocs  : "false",
        modelDocs: "false",
        apis     : "",
        models   : "",
]

}

Steps to reproduce

generate API files using provided options
open any API file
check imports

Start with the provided Gradle GenerateTask configuration and api.json, using the Kotlin generator with the jvm-retrofit2 library and APIs/models-only global properties. Inspect the generated API files for infrastructure imports such as CollectionFormats; done means API-only generation produces files without imports for omitted infrastructure classes.