[BUG] Python Client Code Regex `\n` Handle Problem

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 try to generate python client from this Swagger file, it cannot handle parameter regex validation with \n.

openapi-generator version

4.0.0-beta3

OpenAPI declaration file content or url

https://gist.githubusercontent.com/wy193777/e2da6ad64259cc1ad6a672aae55b1d23/raw/f0ae7cf8bb36458298fd7e0e2ed1b099072d40d3/swagger.json

Command line used for generation

openapi-generator generate -i https://gist.githubusercontent.com/wy193777/e2da6ad64259cc1ad6a672aae55b1d23/raw/f0ae7cf8bb36458298fd7e0e2ed1b099072d40d3/swagger.json -g python -o code\jama-client --skip-validate-spec

Steps to reproduce

Generate client, then run tests.

Related issues/PRs

Suggest a fix

Start by running the provided openapi-generator command with the linked Swagger file and inspect the generated Python client and its tests for the parameter regex containing \n. Compare the generated validation behavior with the declaration, then confirm the fix by regenerating the client and rerunning its tests without mishandling the regex.