GGTS can't run grails unit tests: java.lang.NoClassDefFoundError: org/w3c/dom/ElementTraversal

I've recently upgraded from Java 6 to Java 7, and changed the Grails version accordingly to 2.3.8. Everything compiles and runs fine from the command line.

But I'm finding my version of GGTS (3.5.1.RELEASE) won't run unit tests from within the editor. I get the error: java.lang.NoClassDefFoundError: org/w3c/dom/ElementTraversal

I've tried completely importing the project from scratch - no joy.

Looking at other error reports with the same error, I see this seems to be something to do with versions of xml-apis. I've tried putting compile('xml-apis:xml-apis:2.0.2') in the grails.project.dependency.resolution ... dependencies section of BuildConfig.groovy, but it has no effect.

Any suggestions what I might do instead?

• Charles