Gradle 3.0 "compile" to "implementation" migration doesn't work for fileTree

Question

I'm trying to remove all my lint warnings but I'm stuck with one of the compile to implementation migrations.

If I change this:

    compile fileTree(include: ['*.jar'], dir: 'libs')

to this:

    implementation fileTree(include: ['*.jar'], dir: 'libs')

then the app won't build and I get the following error:

Error:Supertypes of the following classes cannot be resolved. Please make sure you have the required dependencies in the classpath: ... unresolved supertypes: veg.mediaplayer.sdk.MediaPlayer.MediaPlayerCallback

Is this a bug or am I supposed to do something different for fileTree? I couldn't find any explanations looking at the documentation: https://developer.android.com/studio/build/gradle-plugin-3-0-0-migration.html.

I've changed all the other lines in all gradle files from compile to implementation and they all work fine.

Edit: I should also note that this particular module does have a jar in the lib folder. For modules with no jars it works.

Edit 2: I've noticed that actually it doesn't always happen if there is a jar. I have another module with a jar (that I created) and it works fine. Something must be wrong with the mediaplayersdk.jar.

Given that it's only complaining about the callback that is implemented from a file in the jar, I suppose that is where it's getting stuck.

I also tried with Android Studio 3.1.0-beta1 and gradle 4.4 but it didn't help.

Answer 1

Ok I feel like an idiot now. All I had to do was read the documentation more carefully and I would have seen that api is the equivalent of compile and is supported going forward.

Using api works!

i.e. api fileTree(include: ['*.jar'], dir: 'libs')