}

    private static List<String> visitAll(
            Collection<Vertex> children, Map<Vertex, DfsState> stateMap, List<String> list) {
        for (Vertex v : children) {
            DfsState state = stateMap.putIfAbsent(v, DfsState.VISITING);
            if (state == null) {
                visitAll(v.children, stateMap, list);
                stateMap.put(v, DfsState.VISITED);
                list.add(v.label);

        this.reference = (reference != null) ? reference : "";
        this.children = (children != null) ? Collections.unmodifiableList(children) : Collections.emptyList();
    }

    public Throwable getException() {
        return exception;
    }

    public String getMessage() {
        return message;
    }

    public String getReference() {
        return reference;
    }

          <stringParams combine.children="append">
            <!-- NOTE: These values are deliberately not in alpha order! -->
            <stringParam>CHILD-1</stringParam>
            <stringParam>CHILD-3</stringParam>
            <stringParam>CHILD-2</stringParam>
            <stringParam>CHILD-4</stringParam>
          </stringParams>
          <listParam combine.children="append">

    }

    private static List<String> visitAll(
            Collection<Vertex> children, Map<Vertex, DfsState> stateMap, List<String> list) {
        for (Vertex v : children) {
            DfsState state = stateMap.putIfAbsent(v, DfsState.VISITING);
            if (state == null) {
                visitAll(v.children, stateMap, list);
                stateMap.put(v, DfsState.VISITED);
                list.add(v.label);

import org.eclipse.aether.graph.DependencyNode;

class WrapperNode extends AbstractNode {
    protected final Node delegate;
    protected final List<Node> children;

    WrapperNode(Node delegate, List<Node> children) {
        this.delegate = delegate;
        this.children = children;
    }

    @Override
    DependencyNode getDependencyNode() {
        return Utils.cast(AbstractNode.class, delegate, "delegate").getDependencyNode();

import org.eclipse.aether.graph.DependencyNode;

class WrapperNode extends AbstractNode {
    protected final Node delegate;
    protected final List<Node> children;

    WrapperNode(Node delegate, List<Node> children) {
        this.delegate = delegate;
        this.children = children;
    }

    @Override
    DependencyNode getDependencyNode() {
        return Utils.cast(AbstractNode.class, delegate, "delegate").getDependencyNode();

 * @since 4.0.0
 */
@Experimental
@ThreadSafe
@Immutable
public interface XmlNode {

    String CHILDREN_COMBINATION_MODE_ATTRIBUTE = "combine.children";

    String CHILDREN_COMBINATION_MERGE = "merge";

    String CHILDREN_COMBINATION_APPEND = "append";

    /**
     * This default mode for combining children DOMs during merge means that where element names match, the process will

    }

    private static List<String> visitCycle(
            Map<String, Set<String>> graph,
            Collection<String> children,
            Map<String, DfsState> stateMap,
            LinkedList<String> cycle) {
        if (children != null) {
            for (String v : children) {
                DfsState state = stateMap.putIfAbsent(v, DfsState.VISITING);
                if (state == null) {

                .collect(Collectors.toList());
        return new XmlNodeImpl("configuration", null, null, children, null);
    }

    public static org.codehaus.plexus.util.xml.Xpp3Dom convert(MojoDescriptor mojoDescriptor) {
        PlexusConfiguration c = mojoDescriptor.getMojoConfiguration();

        List<XmlNode> children = new ArrayList<>();
        PlexusConfiguration[] ces = c.getChildren();
        if (ces != null) {

        this.parent = parent;
        this.node = (XmlNode) parent.getNode();
        this.children = this.node.getChildren();
        if (startWith != null) {
            Xpp3Dom startWithNode = (Xpp3Dom) startWith.getNode();
            for (; filteredIndex < children.size(); filteredIndex++) {
                if (startWithNode.equals(children.get(filteredIndex))) {
                    filteredIndex++;
                    break;