Proguard, How to obfuscate a code by mapping file

I Develop an android application. and I want to make a function that if tester input class name and method name and parameters in test activity, then invoke any methods in my application by reflection.

in debug mode it is working fine. but in release, proguard obfuscate the method name and class name. so the class name and method name which tester input, is needed to obfuscate. so I searched how to obfuscate codes by mapping file. but I couldn't find any way to solve or similar questions with me.

in Proguard, there is the function of retrace(obfuscated code to normal code) then is it possible that opposite of retrace(normal code to obfuscated code). and if possible then how to realize it?

thanks to read.