[BUG][Python] ModuleNotFoundError when packagename contains dots

Created by: saigiridhar21

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

If we have dots in the packagename (e.g., openapi.client), then required directory structure is getting created like openapi/client. Inside openapi/client/, we will have api and models directories. But, __init__.py files are missing from those sub directories(at openapi and client level). So, the users of this built package will face ModuleNotFoundError: No module named 'openapi' error.

openapi-generator version

4.0.0

OpenAPI declaration file content or url

Command line used for generation

java -jar openapi-generator-cli.jar generate --generator-name python --input-spec openapi-schema.json --output openapi.client --additional-properties packagename=openapi.client

Steps to reproduce

• Generate the SDK using a package name that contains dots e.g., openapi.client.
• Then, build and install the SDK.
• Try to import it in a separate project as a client/user of SDK and run some example code.
• Then, an error will thrown like ModuleNotFoundError: No module named 'openapi'

Related issues/PRs

Suggest a fix

If the packagename contain dots, add __init__.py files at each sub directory level.