How to keep POJO in .aar

Question

I am new to Android and I am trying to develop a .aar that has some services that send data to a remote server. The problem is that when I try to send data in JSON format, the key names are 'a', 'c' .... I know that it is pro guard which is obfuscating the code. How can I avoid this? I tried

-keep public class mypackageName.*

also

-keep public class mypackageName.myClassName**

and also

-keep public class mypackageName.myClassName{*;}
-keepclassmembers class mypackageName.myClassName{*;}

but nothing is working. Which pro guard should I modify the app one or the .aar one?