Grails 2.0.4 and Cobertura not generating XML

I get code coverage generated for a Grails project that I'm working on. But, I would like it to generate xml-files, so e.g. Sonar can disgest it and append it to its reporting.

The command line I'm executing: grails test-app unit: -coverage -xml ... and I get HTML-files ...

I tried adding a coverage section to my BuildConfig.groovy, but it seems to be ignored:

coverage {
        enabledByDefault = true
        xml = true
}

I have tried different versions (1.2.6, 1.2.7 and 2.0.3-3) of the Cobertura plug-in but the result seems the same; nice html-files but no xml.

Something with the version of Grails (2.0.4) in the project in combination with the Cobertura plug-in? Something else I've missed?

Any pointers or suggestions will be appreciated.