public void addArtifact(ArtifactSpec spec) {
            artifacts.put(getKey(spec.artifact), spec);

            String key = spec.artifact.getDependencyConflictId();
            List<ArtifactVersion> artifactVersions = versions.computeIfAbsent(key, k -> new ArrayList<>());
            if (spec.artifact.getVersion() != null) {
                artifactVersions.add(new DefaultArtifactVersion(spec.artifact.getVersion()));
            }

    }

    private Version parseVersion(String spec) {
        try {
            return versionScheme.parseVersion(spec);
        } catch (InvalidVersionSpecificationException e) {
            throw new RuntimeException(e);
        }
    }

    private VersionRange parseVersionRange(String spec) {
        try {
            return versionScheme.parseVersionRange(spec);