[BUG][Typescript-axios] Missing import with only additionalProperties object with array and ref

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 a response returns an object with only additionalProperties of type array with a ref the import is missing in the code generation (as seen in the gist). It does work correctly if the response was an object with additionalProperties of simply that ref for example.

openapi-generator version

4.2.3

OpenAPI declaration file content or url

Swagger JSON

Command line used for generation

Using NodeJS - yarn openapi-generator generate -c config.json --enable-post-process-file -i swagger.json -g typescript-axios -o ./src/openapi
Our config.json is as follows

{
  "withSeparateModelsAndApi": true,
  "modelPackage": "models",
  "apiPackage": "api"
}

(this issue is only relevant if you have withSeparateModelsAndApi enabled)

Steps to reproduce

Simply generate using the provided swagger.json

Related issues/PRs

Suggest a fix

Need to investigate further

Start by running the provided yarn openapi-generator command with swagger.json and config.json, using the linked Swagger JSON as the reproduction case. Inspect the typescript-axios generation path for model import resolution when withSeparateModelsAndApi is enabled. Done means the generated model includes the import for the referenced array type and still handles the non-array additionalProperties case.