[Java] Implemented support for Play! 2.5.x (java8) for retrofit2 client

[lukoyanov]

PR checklist

• Read the contribution guidelines.
• Ran the shell/batch 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)
• Filed the PR against the correct branch: master for non-breaking changes and 2.3.0 branch for breaking (non-backward compatible) changes.

Description of the PR

Support for Play! 2.5.x (java8) for retrofit2 client

[cbornet]

Are we going to pull a new option for each new version of Play ?!

[wing328]

@lukoyanov I agree with @cbornet that we should avoid introducing another option for this case.

For TypeScript Angular2, we recently introduced the option ngVersion so that developers can choose TS Angular 2x or 4x based on their use case.

For your case, I would suggest renaming the option to usePlayWS and make the change (this PR) to 2.3.0 as it's a breaking change.

If users need to use Play! (2.4.x), they can use the master.

[lukoyanov]

@cbornet @wing328 ok, i'll take a look at TS Angular 2x implementation and update this PR.

[wing328]

@lukoyanov if you need any help, just let me know.

[lukoyanov]

I've finished the implementation and improved several things along the way (backport to play24 in #6302). Now Play! support can be enabled via usePlayWS config option, and specific version can be set via playVersion (play24, play25 is supported). @wing328 @cbornet

[lukoyanov]

@wing328 Should I reopen this PR against 3.0 branch?

[wing328]

@lukoyanov sorry I incorrectly closed it. Please still target current master for the change.

3.0.0 is mainly for supporting OpenAPI spec 3.0.

[lukoyanov]

@wing328 Fixed issues after merge.

[lukoyanov]

@wing328 @cbornet Is there something else I should fix/implement here?

[wing328]

@lukoyanov Let me review tomorrow and merge accordingly (sorry too busy these days...)

[wing328]

@lukoyanov I ran ./bin/java-petstore-retrofit2-play25.sh to udpate the petstore sample but got errors running mvn test in samples/client/petstore/java/retrofit2-play25.

Please take a look when you've time.

[lukoyanov]

@wing328 sorry, fixed it.

[wing328]

@lukoyanov np. I performed some tests and the result is good.

Thanks for the enhancement.