Android Build with Gradle and ProGuard : “The output jar must be specified after an input jar, or it will be empty”

Question

I\'m creating a build with different flavors with Gradle. It used to run quite good until now, until I wanted to enable Proguard. I enabled minifyEnabled<

Answer 1

It took quite a while for me to figure it out but, as I had guessed, it was all about Proguard configuration.

I started to dig through the Warnings in the Console and realized that some of the References couldn't be found by Proguard. So adding them as -dontwarn to proguard configuration file solved the problem.

In my case, I had to ignore packages below;

-dontwarn java.lang.invoke**
-dontwarn org.apache.lang.**
-dontwarn org.apache.commons.**
-dontwarn com.nhaarman.**
-dontwarn se.emilsjolander.**