* Traverses this node and potentially its children using the specified visitor.
     *
     * @param visitor the visitor to call back, must not be {@code null}
     * @return {@code true} to visit siblings nodes of this node as well, {@code false} to skip siblings
     */
    boolean accept(@Nonnull NodeVisitor visitor);

    /**
     * Returns a new tree starting at this node, filtering the children.

    /** Value indicating children should be appended as siblings */
    public static final String CHILDREN_COMBINATION_APPEND = "append";
    /**
     * Default mode for combining children DOMs during merge.
     * When element names match, the process will try to merge the element data,
     * rather than putting the dominant and recessive elements as siblings.
     */

     */
    boolean enter(@Nonnull Node node);

    /**
     * Ends the visit to the specified dependency node.
     *
     * @param node the dependency node to visit
     * @return <code>true</code> to visit the specified dependency node's next sibling, <code>false</code> to skip the
     *         specified dependency node's next siblings and proceed to its parent
     */

    protected String version;
    protected String type;
    protected ArtifactScopeEnum artifactScope;
    protected String classifier;

    /**
     * explanation: why this MD was chosen over its siblings
     * in the resulting structure (classpath for now)
     */
    protected String why;

    /** dependencies of the artifact behind this metadata */
    protected Collection<ArtifactMetadata> dependencies;

        // requireNonNull is safe because we checked that not *both* siblings were null.
        keyList.head = requireNonNull(node.nextSibling);
      } else {
        node.previousSibling.nextSibling = node.nextSibling;
      }

      if (node.nextSibling == null) {
        // requireNonNull is safe because we checked that not *both* siblings were null.
        keyList.tail = requireNonNull(node.previousSibling);

            it.value.isNotEmpty()
        } ?: emptyMap()

    /**
     * Returns any temporary directories used to extract resources from jars.
     *
     * These directories will be created as siblings of the randomly assigned test root directories, with the fixed name {@code tmp-extracted-resources}.
     */
    private

     * try to merge the element data, rather than putting the dominant and recessive elements (which share the same
     * element name) as siblings in the resulting DOM.
     */
    @Deprecated(since = "4.0.0", forRemoval = true)
    String DEFAULT_CHILDREN_COMBINATION_MODE = XmlService.DEFAULT_CHILDREN_COMBINATION_MODE;

    }

    public static void addBefore(Node sibling, Closure cl) {
        DomBuilder builder = new DomBuilder(sibling.ownerDocument, null)
        cl.delegate = builder
        cl.call()
        def parent = sibling.parentNode
        builder.elements.each { element ->
            parent.insertBefore(element, sibling)
        }
    }

    public static void addBefore(Element sibling, Node n) {
        def parent = sibling.parentNode

  <version>0.1-SNAPSHOT</version>

  <mailingLists>
    <mailingList>
      <name>blah</name>
    </mailingList>
  </mailingLists>

  <build>
      <testSourceDirectory>../sibling/src-test</testSourceDirectory>
      <sourceDirectory>../sibling/src-main</sourceDirectory>
      <resources>
        <resource><directory>blah</directory></resource>
      </resources>
  </build>

    }

    def resolvesUnqualifiedNameToSiblingClass() {
        ClassMetaData outerClass = Mock()

        when:
        def name = typeNameResolver.resolve('Sibling', classMetaData)

        then:
        name == 'org.gradle.SomeClass.Outer.Sibling'
        _ * classMetaData.innerClassNames >> []
        _ * classMetaData.outerClassName >> 'org.gradle.SomeClass.Outer'