Why do Grails 3 unit tests throw StackOverflowError when run in GGTS (Eclipse)?

Whenever I try to run any unit test in GGTS even as simple as:

void "Test"() {
    expect:
    true
}

I get StackOverflowError. I wonder if it has something to do with GrailsUnitTestMixin.

I've imported my Grails 3 project as a Gradle project in my IDE.