DuplicatedSourceException when using package-info.java file in source package and test package of same name

In our Java project, we have in src/main/java a package x.y.z that contains a file 'package-info.java' for Java doc purposes.
There's also a package x.y.z (i.e. of same name) in src/test/java which contains the related tests. There's also a file 'package-info.java' there.

After doing a 'mvn clean install', running 'mvn sonar:sonar' with version 2.4.1 of the Sonar Maven Plugin worked fine for this project.
However, we have upgraded to version 2.7, and now we get

org.sonar.api.resources.DuplicatedSourceException: x.y.z.package-info
at org.sonar.batch.index.SourcePersister.saveSource(SourcePersister.java:45)

(see attachment for full stacktrace) on 'mvn sonar:sonar' when the 'Sensor JavaSourceImporter' runs.

Where's the problem here?