"library source does not match the bytecode for class" when transitive dependency uses implementation instead of api

I am publishing a Java library that contains a "sources Jar". You can find the `build.gradle` here. The whole minimal reproducible example project is here. 

When the library is used in another project, Android Studio complains that the "library source does not match the bytecode for class" as you can see in the attached screenshot.

The problem appears when my library has a dependncy (I use Gson in the example) :

implementation 'com.google.code.gson:gson:2.8.6'

and declares a class variable of that type. .

If the consumer project adds the same dependancy in its `build.gradle`, then the sources appear normally in Android Studio without a warning . Alternatively, if the library uses API instead of implementation, the problem is not reproduced:

api'com.google.code.gson:gson:2.8.6'

Is this a bug? The produced jar files in my  MavenLocal repo are here.