return artifact.getGroupId() + ':' + artifact.getArtifactId() + ':' + artifact.getBaseVersion();
    }

    @Override
    protected void merge(Metadata recessive) {
        metadata.getVersioning().setLastUpdatedTimestamp(timestamp);

        String lastUpdated = metadata.getVersioning().getLastUpdated();

        Map<String, SnapshotVersion> versions = new LinkedHashMap<>();

        for (Artifact artifact : artifacts) {

            snapshot.setTimestamp(utcDateFormatter.format(timestamp));

            Versioning versioning = new Versioning();
            versioning.setSnapshot(snapshot);
            versioning.setLastUpdatedTimestamp(timestamp);
            lastUpdated = versioning.getLastUpdated();

            metadata.setVersioning(versioning);
        } else {
            snapshot = metadata.getVersioning().getSnapshot();

        return metadata;
    }

    @Override
    protected void merge(Metadata recessive) {
        Versioning versioning = metadata.getVersioning();
        versioning.setLastUpdatedTimestamp(timestamp);

        if (recessive.getVersioning() != null) {
            if (versioning.getLatest() == null) {
                versioning.setLatest(recessive.getVersioning().getLatest());
            }