_ * classDoc.classExtensions >> []
        def subtypes = [ "org.gradle.Subtype1", "org.gradle.Subtype2", "org.gradle.Subtype3", "org.gradle.Subtype4" ].collect {
            ClassDoc subtype = Mock()
            _ * subtype.name >> it
            subtype
        }
        _ * classDoc.subClasses >> subtypes

        when:
        def result = parse('<root/>')
        withCategories {