Test.groovy

import org.springframework.beans.factory.annotation.Autowired
import ratpack.handling.Chain
import ratpack.http.client.HttpClient

// project 1
// no dependencies
interface Service {
    void doRequest()
}

// project 2
// depends on ratpack, project 1
class Handler {

    // ServiceImpl instance
    @Autowired
    Service service

    def execute(Chain chain) {
        chain.path('doRequest') { ctx ->
            HttpClient httpClient = ctx.get(HttpClient)
            service.doRequest()
        }
    }

}

// project 3
// depends on ratpack, project 1, project 2
class ServiceImpl implements Service {
    void doRequest() {
        // need HttpClient
    }
}