Fix for ENUM requires https://github.com/swagger-api/swagger-codegen-generators/pull/978

[sbilello]

PR checklist

• Read the contribution guidelines.
• Ran the shell script under ./bin/ to update Petstore sample so that CIs can verify the change. (For instance, only need to run ./bin/{LANG}-petstore.sh and ./bin/security/{LANG}-petstore.sh if updating the {LANG} (e.g. php, ruby, python, etc) code generator or {LANG} client's mustache templates). Windows batch files can be found in .\bin\windows\.
• Filed the PR against the correct branch: 3.0.0 branch for changes related to OpenAPI spec 3.0. Default: master.
• Copied the technical committee to review the pull request if your PR is targeting a particular programming language.

Description of the PR

This PR needs to be merged after swagger-api/swagger-codegen-generators#978

@frantuma

mvn test

[INFO] Reactor Summary for swagger-codegen-project 3.0.30-SNAPSHOT:
[INFO] 
[INFO] swagger-codegen-project ............................ SUCCESS [  0.498 s]
[INFO] swagger-codegen (core library) ..................... SUCCESS [ 13.882 s]
[INFO] swagger-codegen (executable) ....................... SUCCESS [  2.700 s]
[INFO] swagger-codegen (maven-plugin) ..................... SUCCESS [  3.798 s]
[INFO] swagger-generator .................................. SUCCESS [  5.670 s]
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  26.865 s
[INFO] Finished at: 2021-10-11T12:06:20-07:00
[INFO] ------------------------------------------------------------------------

It needs the mvn clean install from
swagger-api/swagger-codegen-generators#978
to make it work.

If you encounter any problem please provide specific steps to replicate it

Thanks

[sbilello]

I am going to close this PR and create a new one to have a clear git history

[frantuma]

@sbilello thanks, opened PR #11250 addressing that

[sbilello]

@frantuma I created #11251