Are you purposefully trying to deviate from the Launcher specs? We probably need to rewrite the underlying components of Launcher specs to use the GradleConnector. But until then we should use the same structures, i.e. use Launcher for now. And we can convert to the GradleConnector fully, like in the gradle-test-kit (https://github.com/alkemist/gradle-test-kit/blob/master/src/main/java/org/gradle/testkit/functional/internal/toolingapi/ToolingApiGradleHandleFactory.java)