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

        Versioning.Builder versioning = Versioning.newBuilder(original);
        versioning.lastUpdated(fmt.format(timestamp));

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

    }

    @Override
    protected void merge(Metadata recessive) {
        metadata = metadata.withVersioning(metadata.getVersioning().withLastUpdated(fmt.format(timestamp)));

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

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

        for (Artifact artifact : artifacts) {

            utcDateFormatter.setCalendar(new GregorianCalendar());
            utcDateFormatter.setTimeZone(DEFAULT_SNAPSHOT_TIME_ZONE);

            snapshot = Snapshot.newBuilder()
                    .buildNumber(buildNumber != null ? buildNumber : getBuildNumber(recessive) + 1)
                    .timestamp(utcDateFormatter.format(this.timestamp))
                    .build();

                // Message below is checked for in the MNG-2199 core IT.
                throw new ModelResolverException(
                        String.format("The requested version range '%s' does not specify an upper bound", version),
                        groupId,
                        artifactId,
                        version);
            }

 * is meant for exclusive consumption by the model builder and is opaque to the cache implementation. The cache key is
 * formed by a combination of group id, artifact id, version and tag. The first three components generally refer to the
 * identity of a model. The tag allows for further classification of the associated data on the sole discretion of the