Jackson vs. Android package optimization

 For some weird reason (including a 20MB text file to be precise) I wanted to turn on 

shrinkResources true
minifyEnabled true

in my Android app.

I did the compression alright, but the app stopped working.

I got weird Exceptions like 

Cannot construct instance of `g1.k` (no Creators, like default ...)

Well that pointed me to obfuscation, because I definitely don't have classes and members like that.

Jackson relies on reflection to find your class properties and getter/setter functions, so you should not obfuscate them. Duuuh.

They way to turn that off is in the proguard-rules.pro file.

-keepattributes *Annotation*,EnclosingMethod,Signature
-keepnames class com.fasterxml.jackson.** { *; }
-dontwarn com.fasterxml.jackson.databind.**
-keep public class at.roman.traininfo.data.** {
*;
}

The last part keeps the whole package where all my entity classes are.