[BUG][PHP] Modern syntax option breaks/overrides custom template directory

Bug Report Checklist

• [x ] Have you provided a full/minimal spec to reproduce the issue?
• [ x] Have you validated the input using an OpenAPI validator (example)?
• [x ] Have you tested with the latest master to confirm the issue still exists?
• [ x] Have you searched for related issues/PRs?
• [x ] What's the actual output vs expected output?
• [Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

The custom template directory is not being used in the mezzio generator when the modern option is enabled.

openapi-generator version

6.3.0

OpenAPI declaration file content or url

Any will do

Generation Details

java -jar openapi-generator-cli.jar generate -g php-mezzio-ph -i api.yaml -o php-mezzio -t mezzio --additional-properties=modern=1

Steps to reproduce

Create a custom template directory with a customized php mezzio (modern) template file and generate using the custom template directory and the modern option. The generated output will not contain the customized output.

java -jar openapi-generator-cli.jar generate -g php-mezzio-ph -i api.yaml -o php-mezzio -t mezzio --additional-properties=modern=1

Related issues/PRs

n/a

Suggest a fix

The template directory is set regardless of commandl line arg or configuration in PhpMezzioPathHandlerServerCodegen.java on line 129. Although not a suitable fix, for my purposes, I am working around this by simply commenting this line.

Start with PhpMezzioPathHandlerServerCodegen.java, especially line 129 where the template directory is set, and reproduce the issue with the provided openapi-generator command using --additional-properties=modern=1. Verify the generated PHP Mezzio output with a customized template. Done means the custom template directory is honored when the modern option is enabled.