`module-info.class` is added to sources and javadoc jars

I'm using:

```kotlin
java {
    withJavadocJar()
    withSourcesJar()
}

modularity {
    mixedJavaRelease(8)
}
```

And this seems to add `module-info.class` to the javadoc jar and the sources jar. I can exclude them manually, but should it be the case by default? Or is that a bug?