spec = new ArtifactSpec();
            spec.artifact = artifact;
            source.addArtifact(spec);
        }
        return spec;
    }

    @SuppressWarnings("unchecked")
    private static Set<Artifact> createSet(Object[] x) {
        return new LinkedHashSet(Arrays.asList(x));
    }

    private class ArtifactSpec {
        private Artifact artifact;