buildFile << """
        @Managed interface CustomLanguageSourceSet extends LanguageSourceSet {}

        class CustomLanguagePlugin extends RuleSource {
            @ComponentType
            void declareCustomLanguage(TypeBuilder<CustomLanguageSourceSet> builder) {
            }
        }

        apply plugin:CustomLanguagePlugin
"""
    }

    def "can add custom language sourceSet to component"() {
        when: