return factory;
    }

    /**
     * Creates a new instance of {@link SAXParser} using the default configuration of {@link SAXParserFactory}.
     *
     * @return A new instance of {@link SAXParser}.
     */
    public static SAXParser newSAXParser() {
        return newSAXParser(newInstance());
    }

    /**
     * Creates a new instance of {@link SAXParser} using the specified {@link SAXParserFactory}.
     *

    public static synchronized final SingletonContext getInstance() {
        if (INSTANCE == null) {
            try {
                log.debug("Initializing singleton context");
                init(null);
            } catch (final CIFSException e) {
                log.error("Failed to create singleton JCIFS context", e);
            }
        }
        return INSTANCE;
    }

    /**

     * @param index The index name.
     * @return This builder instance.
     */
    public PopularWordsRequestBuilder setIndex(final String index) {
        request.setIndex(index);
        return this;
    }

    /**
     * Sets the size of results for the request.
     * @param size The size.
     * @return This builder instance.
     */
    public PopularWordsRequestBuilder setSize(final int size) {

    }

    /**
     * Returns the Fess configuration instance.
     *
     * @return the Fess configuration
     */
    @Override
    public FessConfig getFessConfig() {
        return fessConfig;
    }

    /**
     * Returns the logger instance for this class.
     *
     * @return the logger instance
     */
    @Override
    public Logger getLogger() {

    }

    /**
     * Retrieves the current thread-local instance of the UrlQueueService.
     *
     * @return the UrlQueueService instance associated with the current thread.
     */
    public static UrlQueueService<UrlQueue<?>> getUrlQueueService() {
        return URL_QUEUE_SERVICE_THREAD_LOCAL.get();
    }

    /**
     * Sets the UrlQueueService instance to the thread-local variable.

     */
    boolean embedded();

    /**
     * Creates a new Builder instance for constructing a Maven ParserRequest.
     *
     * @param args the command-line arguments
     * @param messageBuilderFactory the factory for creating message builders
     * @return a new Builder instance
     */
    @Nonnull

            childUrlRuleMap.put(tagName, attrName);
        }
    }

    /**
     * Gets the XPath API instance for this thread.
     *
     * @return the XPath API instance
     */
    protected XPathAPI getXPathAPI() {
        XPathAPI cachedXPathAPI = xpathAPI.get();
        if (cachedXPathAPI == null) {
            cachedXPathAPI = new XPathAPI();

          .put(IndexOutOfBoundsException.class, e -> e instanceof IndexOutOfBoundsException)
          .put(NoSuchElementException.class, e -> e instanceof NoSuchElementException)
          .put(NullPointerException.class, e -> e instanceof NullPointerException)
          .put(NumberFormatException.class, e -> e instanceof NumberFormatException)
          .put(RuntimeException.class, e -> e instanceof RuntimeException)

          .put(IndexOutOfBoundsException.class, e -> e instanceof IndexOutOfBoundsException)
          .put(NoSuchElementException.class, e -> e instanceof NoSuchElementException)
          .put(NullPointerException.class, e -> e instanceof NullPointerException)
          .put(NumberFormatException.class, e -> e instanceof NumberFormatException)
          .put(RuntimeException.class, e -> e instanceof RuntimeException)

    for (Class<?> mutableClass : mutableClasses) {
      Object instance = ArbitraryInstances.get(mutableClass);
      assertNotNull("Expected to return non-null for: " + mutableClass, instance);
      assertNotSame(
          "Expected to return fresh instance for: " + mutableClass,
          instance,
          ArbitraryInstances.get(mutableClass));
    }
  }

  private enum EmptyEnum {}