[BUG] Kotlin multiplatform requires auth methods

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• What's the version of OpenAPI Generator used?
• Have you search for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Bounty to sponsor the fix (example)

Description

When generating a new client with the kotlin generator and the multiplatform library, if your spec has no api endpoints that require any authentication methods, the generated client will have errors and a private authentications property will be generated with lazy instantiation block of:

{
    mapOf()
}

openapi-generator version

4.3.1

OpenAPI declaration file content or url

Works with any declaration that contains zero authorizations: arrays.

Command line used for generation

openapi-generator generate -g kotlin --library multiplatform -o kotlin_client -i test.yaml

Steps to reproduce

• Grab a valid openapi spec with no authorizations for any endpoints
• Generate a kotlin multiplatform client
• Try to build a native library from the generated client code, e.g.: ./gradlew clean jvmJar

Related issues/PRs

Suggest a fix

I submitted a PR to fix the issue. More work regarding the kotlin mutliplatform library needs to be done for sure though: https://github.com/OpenAPITools/openapi-generator/pull/6983

Start with the Kotlin multiplatform generation command and a valid OpenAPI spec containing no authentication requirements. Build the generated client with ./gradlew clean jvmJar and inspect the generated private authentications property and its lazy mapOf() block. Done means a no-authentication specification produces a client that builds successfully; PR #6983 is linked as prior work.