New gradle plugin version (4.1.0): no longer returning any ressource fields

Issue

To get all drawables in an android app (using Kotlin) I call R.drawable::class.java.fields.
Since yesterday it worked perfectly fine but as I updated

classpath "com.android.tools.build:gradle:4.0.2"  

to

classpath "com.android.tools.build:gradle:4.1.0"

it just returns an empty array (so no fields / drawables are found).

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I changed anything other than this and also tried to clean the project, rebuild it, invalidate android studio caches and to downgrade and upgrade again, but nothing worked for me.

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Why is that and is there a way to fix that weird bug?

Solution

I found a solution:

I made it working by explicitly exluding the fields out of resource shrinking by adding an entry to the proguard rules as explained here: https://github.com/mikepenz/AboutLibraries/issues/331

You just have to add the following to the proguard-rules.pro file for your app module:

-keep class **.R$* {
    <fields>;
}

Answered By - ByteFanatic