[Java][jersey2] Add debugging to OAuth

[wing328]

• better code format
• setting debugging in service
• more logging

To close #6461

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cc @bbdouglas (2017/07) @sreeshas (2017/08) @jfiala (2017/08) @lukoyanov (2017/09) @cbornet (2017/09) @jeff9finger (2018/01) @karismann (2019/03) @Zomzog (2019/04) @lwlee2608 (2019/10) @bkabrda (2020/01)

[wing328]

Travis tests passed via https://travis-ci.org/github/OpenAPITools/openapi-generator/builds/701273310