// TODO use newest conflict resolver
        ArtifactSpec a = createArtifactSpec("a", "1.0");
        ArtifactSpec b1 = a.addDependency("b", "1.0");
        ArtifactSpec c = a.addDependency("c", "1.0");
        ArtifactSpec d2 = b1.addDependency("d", "2.0");
        d2.addDependency("h", "1.0");
        ArtifactSpec d1 = c.addDependency("d", "1.0");