public void push(Element element) {
        stack.getFirst().appendChild(element);
        stack.addFirst(element);
    }

    public Element pop() {
        Element element = stack.removeFirst();
        if (emptyPara(element)) {
            element.getParentNode().removeChild(element);
        }
        return element;
    }

    private boolean emptyPara(Element element) {

     * @param o
     *            element whose presence in this set is to be tested.
     * @return true if this set contains the specified element.
     */
    @Override
    public boolean contains(final Object o) {
        return map.containsKey(o);
    }

    /**
     * Adds the specified element to this set if it is not already present.
     *
     * @param o
     *            element to be added to this set.

  @Override
  public int indexOf(@CheckForNull Object element) {
    return delegate().indexOf(element);
  }

  @Override
  public int lastIndexOf(@CheckForNull Object element) {
    return delegate().lastIndexOf(element);
  }

  @Override
  public ListIterator<E> listIterator() {
    return delegate().listIterator();
  }

  @Override
  public ListIterator<E> listIterator(int index) {

        this.parent = parent
    }

    protected Element createNode(Object name) {
        Element element = document.createElement(name as String)
        if (getCurrent() == null) {
            elements << element
            parent?.appendChild(element)
        }
        return element
    }

    protected Element createNode(Object name, Map attributes) {
        Element element = createNode(name)
        attributes.each {key, value ->

  // Query Operations

  /**
   * Returns the number of occurrences of {@code element} in this multiset.
   *
   * @param element the element to look for
   * @return the nonnegative number of occurrences of the element
   */
  @Override
  public int count(@CheckForNull Object element) {
    AtomicInteger existingCounter = safeGet(countMap, element);
    return (existingCounter == null) ? 0 : existingCounter.get();
  }

  }

  /**
   * Adds the given element to this queue. If this queue has a maximum size, after adding {@code
   * element} the queue will automatically evict its greatest element (according to its comparator),
   * which may be {@code element} itself.
   *
   * @return {@code true} always
   */
  @CanIgnoreReturnValue
  @Override
  public boolean add(E element) {
    offer(element);
    return true;
  }

  }

  protected void expectMissingKeys(K... elements) {
    for (K element : elements) {
      assertFalse("Should not contain key " + element, getMap().containsKey(element));
    }
  }

  protected void expectMissingValues(V... elements) {
    for (V element : elements) {
      assertFalse("Should not contain value " + element, getMap().containsValue(element));
    }
  }

import org.w3c.dom.Document;
import org.w3c.dom.Element;

public class ElementWarningsRenderer {
    public void renderTo(DslElementDoc elementDoc, String type, Element parent) {
        if (elementDoc.isDeprecated()) {
            Document document = parent.getOwnerDocument();
            Element caution = document.createElement("caution");
            parent.appendChild(caution);
            Element para = document.createElement("para");

    }

    public void renderTo(MethodDoc methodDoc, Element parent) {
        Document document = parent.getOwnerDocument();

        Element section = document.createElement("section");
        parent.appendChild(section);
        section.setAttribute("id", methodDoc.getId());
        section.setAttribute("role", "detail");

        Element title = document.createElement("title");
        section.appendChild(title);

    }

    /**
     * {@link Element}を文字列に変換します。
     *
     * @param element
     *            要素。{@literal null}であってはいけません
     * @return 変換された文字列
     */
    public static String toString(final Element element) {
        assertArgumentNotNull("element", element);

        final StringBuilder buf = new StringBuilder(1000);
        appendElement(element, buf);
        return new String(buf);
    }