this project's detail described in below question.

http://stackoverflow.com/questions/42327762/proguards-shrinking-step-doesnt-figure-out-methods-which-overrided-from-fragme

in additional, after check the source code of android-plugin 1.3.1, I use java reflection to take the android proguard files in memory and add my extra proguard file during runtime, it my little trick ^_^.