[Python] Support for package hierarchy

Description

I am trying to generate a service client for a project that uses a particular package hierarchy by convention. I have tried the following but am yet to generate a client that I can successfully import, due to mis-matching/incorrect import statements, and files that are placed in the wrong folders.

For example #1 (below) I get code like import api where import foo.bar.baz.api is desired. With example #2, I get directories like foo.bar.baz.my_client.model when foo/bar/baz/my_client/model is desired.

ex.1)

openapi-generator generate -g python -l python -c my_config.json \
    --api-package api --model-package model \
    --http-user-agent 'my_agent' \
    --log-to-stderr \
    -i ./api/my_spec.yaml -o $CLIENT_DIR

ex.2)

openapi-generator generate -g python -l python -c my_config.json \
    --api-package foo.bar.baz.my_client.api --model-package foo.bar.baz.my_client.model \
    --http-user-agent 'my_agent' \
    --log-to-stderr \
    -i ./api/my_spec.yaml -o $CLIENT_DIR

my_config.json:

  "packageName":"foo.bar.baz.my_client",
  "projectName":"my_project",
  "packageVersion": "1.0.0",
  "sortParamsByRequiredFlag": "true",
  "hideGenerationTimestamp": "true",
  "generateSourceCodeOnly": "false",
  "library": "urllib3"
}

openapi-generator version

3.3.1

OpenAPI declaration file content or url

I don't believe this is relevant. If needed I can provide a version of the spec.

Command line used for generation

See above.

Steps to reproduce

Run either of the commands above.

Related issues/PRs

I didn't find any.

Suggest a fix/enhancement

It seems like there is some code that is parsing the "foo.bar.baz" syntax into a file path since some of the files are correctly placed with the right import statements. Presumably some of the generator code (the part that handles --api-package api --model-package model) is not correctly handling these package names.

Thanks for reviewing this. Any pointers/suggestions would be really appreciated!

Start by reproducing the issue with my_config.json, ./api/my_spec.yaml, and the two openapi-generator commands shown. Trace the Python generator's handling of --api-package, --model-package, and packageName; done means dotted package names produce matching directory paths and import statements in the generated client.