[BUG] Inconsistent openapitools.json handling beetwen npm and docker version of openapi-generator-cli

🐛 Bug Report:

Describe the bug

I want to configure generation in CLI in some kind of config file. When using (npm) generator-cli readme says that you can configure it with openapitools.json file and later use openapi-generator-cli generate --generator-key YOUR_GENERATOR_KEY but on the other hand if you want to use (docker) generator-cli this kind of configuration is unexpected.

Steps to Reproduce

Given such a config (config/config.json) file:

{
  "$schema": "node_modules/@openapitools/openapi-generator-cli/config.schema.json",
  "spaces": 2,
  "generator-cli": {
    "version": "6.1.0",
    "generators": {
      "v3.0": {
        "generatorName": "spring",
        "output": "/local",
        "inputSpec": "https://raw.githubusercontent.com/swagger-api/swagger-petstore/master/src/main/resources/openapi.yaml",
        "globalProperty": {
          "models": "Order,User",
        },
        "additionalProperties": {
          "apiPackage": "com.test",
          "modelPackage": "com.test.model",
          "supportingFilesToGenerate": "ApiUtil.java",
          "groupId": "com.test",
          "artifactId": "test",
          "artifactVersion": "0.0.0",
          "interfaceOnly": true
        }
      }
    }
  }
}

Command:

docker run --rm -v "${PWD}/tmp:/local" -v "${PWD}/config/config.json:/openapitools.json" openapitools/openapi-generator-cli:v6.1.0 generate --generator-key v3.0

Produces:

[error] Found unexpected parameters: [--generator-key, v3.0]

See 'openapi-generator-cli help' for usage.

Expected behavior

Consistent behavior for both npm generator-cli and docker generator-cli.

Operation System:

• OS: Windows
• Version 10

Package System:

No package system, just docker:

• Docker version 20.10.17, build 100c701

Additional context

IMO it should be well documented (and consistent) how to configure all of configuration properties (global and additional) by CLI using some kind of config file for both npm and docker CLI as it is helpful in CI/CD tools.