R8 minify: Type defined multiple times

Question

When building a signed release APK I'm getting following error:

.gradle/caches/transforms-2/files-2.1/532a317ccd54c8ae4f622faeb8b534a9/jetified-wordup-core-0.2.1-runtime.jar:de/codereddev/wordup/database/WordDao_Impl$5.class,
Type de.codereddev.wordup.database.WordDao_Impl$5 is defined multiple times:
/home/codered_dev/.gradle/caches/transforms-2/files-2.1/532a317ccd54c8ae4f622faeb8b534a9/jetified-wordup-core-0.2.1-runtime.jar:de/codereddev/wordup/database/WordDao_Impl$5.class,
/home/codered_dev/MySoundboardApp/app/build/intermediates/javac/release/classes/de/codereddev/wordup/database/WordDao_Impl$5.class

This Room DAO definition comes from a library I created myself.

Looking into the .jar file I can find this:

This only happens on release. I can still build and run debug without any problems.

Unfortunately I can't find the error. Hopefully anyone here might have a hint for me.

I first assumed it might be due to the fact that the library contains a standard definition of a Room database and my application using the library contains its own custom definition holding the same DAOs. So annotation processors would maybe process the DAOs twice. But I couldn't check this properly.

If it's important to know: I'm also using Koin for dependency injection.

Answer 1

Unfortunately I don't exactly know the reason but I got the library working by removing the Room kaptCompiler from the library and instead only have it in the app that is using the library.

Answer 2

This can happen if the same package is used by different module, e.g. a library and the app using the library both using org.foo.bar as package. If different packages are used, the error will go away.