}

            Collection<String> versions =
                    new LinkedHashSet<>(recessive.getVersioning().getVersions());
            versions.addAll(versioning.getVersions());
            versioning.setVersions(new ArrayList<>(versions));
        }

        // just carry-on as-is
        if (!recessive.getPlugins().isEmpty()) {

     */
    @Nonnull
    List<Version> getVersions();

    /**
     * Gets the lowest version matching the requested range.
     *
     * @return An Optional containing the lowest matching version, or empty Optional if no versions
     *         matched the requested range
     */
    @Nonnull
    default Optional<Version> getLowestVersion() {
        return getVersions().isEmpty()
                ? Optional.empty()

                    plugin.setVersion(versions.get(plugin.getKey()));
                    if (plugin.getVersion() == null) {
                        PluginVersionRequest request = new DefaultPluginVersionRequest(
                                plugin, session.getRepositorySession(), project.getRemotePluginRepositories());
                        plugin.setVersion(pluginVersionResolver.resolve(request).getVersion());

        final Parent parent = new Parent();
        parent.setGroupId("ut.simple");
        parent.setArtifactId("artifact");
        parent.setVersion("0");

        UnresolvableModelException e = assertThrows(
                UnresolvableModelException.class,
                () -> newModelResolver().resolveModel(parent),

    } // -- void setGroupId( String )

    /**
     * Set the version of the extension.
     *
     * @param version a version object.
     */
    public void setVersion(String version) {
        this.version = version;
    } // -- void setVersion( String )

    /**
     * Gets the identifier of the extension.
     *

        Metadata metadata = new Metadata();
        metadata.setVersioning(versioning);
        metadata.setGroupId(artifact.getGroupId());
        metadata.setArtifactId(artifact.getArtifactId());
        metadata.setVersion(artifact.getBaseVersion());
        metadata.setModelVersion("1.1.0");
        return metadata;
    }

    public void bind(Artifact artifact) {
        artifacts.add(artifact);
    }

    @Deprecated

     */
    public int getVersion() {
        return version;
    }

    /**
     * Sets the witness protocol version.
     *
     * @param version the protocol version
     */
    public void setVersion(int version) {
        this.version = version;
    }

    /**
     * Gets the share name to monitor.
     *
     * @return the share name
     */
    public String getShareName() {

        if (Artifact.LATEST_VERSION.equals(version) || Artifact.RELEASE_VERSION.equals(version)) {
            // meta-versions are not valid <version/> values...don't write them.
            metadata.setVersion(null);
        }

        if (changed || !metadataFile.exists()) {
            metadataFile.getParentFile().mkdirs();
            try (OutputStream output = Files.newOutputStream(metadataFile.toPath())) {

        this.source = source;
        this.model = model;
        setGroupId(groupId);
        setArtifactId(artifactId);
        setVersion(version);
    }

    public ModelSource getSource() {
        return source;
    }

    /**
     * Gets the model being wrapped.
     *
     * @return The model or {@code null} if not set.
     */

        CoreExtension oldExtension = new CoreExtension();
        oldExtension.setGroupId(extension.getGroupId());
        oldExtension.setArtifactId(extension.getArtifactId());
        oldExtension.setVersion(extension.getVersion());
        if (extension.getClassLoadingStrategy() != null) {
            oldExtension.setClassLoadingStrategy(extension.getClassLoadingStrategy());
        }
        this.extension = oldExtension;