This was added via #684 and later rolled back with #687
According to the reason to rollback:

It turns out that DexGuard doesn't use those tasks for mapping.txt generation: rather, both the mapping and apk packaging are done within the same dexguard task.
The aforementioned approach only worked when there was a cached mapping.txt present.

@bruno-garcia Nowhere in either of those PRs can you find the task that I'm adding transformClassesAndDexWithShrinkResFor${variant.name.capitalize()}. Note ShrinkRes in mine, not Resources.

This is what I have for my builds to generate and correctly package the sentry asset file into my apk

 def proguardTask = project.tasks.findByName("transformClassesAndResourcesWithR8ForRelease")
 def dexTask = project.tasks.findByName("transformClassesAndDexWithShrinkResForRelease")

I use R8, minification, and resource shrinking

@codeniko You're right. I had the task names wrong.
Thanks for the fix!
/cc @justacodefan Could you please make sure this doesn't affect your fix for AGP 3.4.0?