[REQ][JAVA] Replace apache oltu with scribejava for java generator

[valmoz]

Description
Currently, the Java generator uses Oltu to perform oauth requests.

Apache Oltu has been moved into the Attic in April 2018, so it's not actively maintained anymore. It would be great to replace Oltu with Scribejava (or at least to add an option to select the oauth library), like already did for the java-feign generator in this issue:
#8297

openapi-generator version
5.2.1

[wing328]

I think jersey2 also uses Scribejava instead of Oltu.

For other libraries, may I know if you've time to contribute a PR with the enhancement?

[valmoz]

I can try, first time using mustache :)

[DEV-Cristian96]

Any news?

[barbetb]

Is there any movement on this topic? Oltu is retired since 2016.

[wing328]

@barbetb can you please submit a PR on top of #10965 with resolved merge conflicts? thank you.