PHP Code generation - Why forcing Guzzle usage

Description

Recently I opened an issue on a project which uses the swagger-codegen to generate a PHP lib.

Related issues/PRs

https://github.com/sendinblue/APIv3-php-library/issues/194

Suggest a fix/enhancement

This is my original message :

Recently I had to use the SendinBlue API in my PHP project.
What was my surprise when I saw I had to download Guzzle (via composer of course).
I already developped a small lib to comunicate with another API and I didn't force the lib user to use a specific implementation for the http calls. The user have to give an implementation of a PSR ClientInterface.
This way, the user can use whatever implementation he wants.
Furthermore, if I have to call x differents API and each lib chose a different implementation for the HTTP calls, the project downloads a lot of different projects to do the same thing …

Could you change that and offer to the users (other devs) the choice ? Whatever lib wich respect PSR-7, 17 and 18 ?

In my PHP lib project, for exemple, I use HTTPlug (https://docs.php-http.org/en/latest/httplug/introduction.html) and I don't need to specify a specific lib.

No files or tests are named. Start by locating the PHP generator templates and dependency declarations that introduce Guzzle, then review the linked SendinBlue issue and the PSR-7, PSR-17, and PSR-18 requirements. Done means generated clients offer a compatible HTTP-client choice instead of forcing Guzzle, with the resulting dependency behavior documented and verified.