* 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.

     */
    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;

     * 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.
     */
    String DEFAULT_CHILDREN_COMBINATION_MODE = CHILDREN_COMBINATION_MERGE;

    String SELF_COMBINATION_MODE_ATTRIBUTE = "combine.self";

    String SELF_COMBINATION_OVERRIDE = "override";

        // 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);

      return index;
    }

    // About the term "aunt node": it's better to leave gender out of it, but for this the English
    // language has nothing for us. Except for the whimsical neologism "pibling" (!) which we
    // obviously could not expect to increase anyone's understanding of the code.

    /**
     * Swap {@code actualLastElement} with the conceptually correct last element of the heap.

      createFile(right.resolve("another.txt"));

      createSymbolicLink(left.resolve("sibling"), right);
      createSymbolicLink(right.resolve("sibling"), left);
      assertEquals(
          ImmutableSet.of(
              new ResourceInfo(FILE, "left/some.txt", loader),
              new ResourceInfo(FILE, "left/sibling/another.txt", loader),
              new ResourceInfo(FILE, "right/another.txt", loader),

   * the path {@code a/../b}, which {@code simplifyPath} will change to {@code b}. If {@code a} is a
   * symlink to {@code x}, {@code a/../b} may refer to a sibling of {@code x}, rather than the
   * sibling of {@code a} referred to by {@code b}.
   *
   * @since 11.0
   */
  public static String simplifyPath(String pathname) {
    checkNotNull(pathname);
    if (pathname.length() == 0) {