[BUG] docker version of openapi-generator-cli doesn't recognize `openapitools.json`

[scarf005]

🐛 Bug Report:

docker version of openapi-generator-cli doesn't work with configuration files.

Steps to Reproduce

https://github.com/OpenAPITools/openapi-generator-cli/blob/11a2df547ef2f54d714a37da9b3f4dcb29c69c46/apps/generator-cli/src/README.md?plain=1#L161-L162

despite the documentation, following doesn't work:

openapitools.json:

{
  "$schema": "https://raw.githubusercontent.com/OpenAPITools/openapi-generator-cli/refs/heads/master/apps/generator-cli/src/config.schema.json",
  "spaces": 2,
  "generator-cli": {
    "version": "7.12.0",
    "generators": {
      "v3.0": {
        "inputSpec": "https://touhoudb.com/swagger/v1/swagger.json",
        "generatorName": "typescript-fetch",
        "output": "#{cwd}/client"
      }
    }
  }
}

podman run --rm -v $PWD:/local:z openapitools/openapi-generator-cli generate
[error] Required option '-i' is missing

even if i explicitly pass in config file, it doesn't read config file despite "generatorName": "typescript-fetch",

podman run --rm -v $PWD:/local:z openapitools/openapi-generator-cli generate --config /local/openapitools.json
Exception in thread "main" java.lang.NullPointerException: generator name must be specified
        at java.base/java.util.Objects.requireNonNull(Unknown Source)
        at org.apache.commons.lang3.Validate.notEmpty(Validate.java:388)
        at org.openapitools.codegen.config.CodegenConfigurator.toContext(CodegenConfigurator.java:643)
        at org.openapitools.codegen.config.CodegenConfigurator.toClientOptInput(CodegenConfigurator.java:744)
        at org.openapitools.codegen.cmd.Generate.execute(Generate.java:527)
        at org.openapitools.codegen.cmd.OpenApiGeneratorCommand.run(OpenApiGeneratorCommand.java:32)
        at org.openapitools.codegen.OpenAPIGenerator.main(OpenAPIGenerator.java:66)

Expected behavior

docker version works the same like the npm version.

Screenshots

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Operation System (please complete the following information):

• OS: Fedora Linux
• Version 41

Package System (please complete the following information):

• Version rpm 4.20.0

Additional context

Add any other context about the problem here.