/*
    * Copyright (c) 2002-2025 Gargoyle Software Inc.
    *
    * Licensed under the Apache License, Version 2.0 (the "License");
    * you may not use this file except in compliance with the License.
    * You may obtain a copy of the License at
    * https://www.apache.org/licenses/LICENSE-2.0
    *
    * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.htmlunit;
  
  import static java.nio.charset.StandardCharsets.ISO_8859_1;
  import static java.nio.charset.StandardCharsets.UTF_8;
  import static org.htmlunit.BrowserVersionFeatures.HTTP_HEADER_CH_UA;
  import static org.htmlunit.BrowserVersionFeatures.HTTP_HEADER_PRIORITY;
  
  import java.io.BufferedInputStream;
  import java.io.File;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.ObjectInputStream;
  import java.io.Serializable;
  import java.lang.ref.WeakReference;
  import java.net.MalformedURLException;
  import java.net.URL;
  import java.net.URLConnection;
  import java.net.URLDecoder;
  import java.nio.charset.Charset;
  import java.nio.file.Files;
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.ConcurrentModificationException;
  import java.util.Date;
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.Iterator;
  import java.util.LinkedHashMap;
  import java.util.LinkedHashSet;
  import java.util.List;
  import java.util.Locale;
  import java.util.Map;
  import java.util.Objects;
  import java.util.Optional;
  import java.util.Set;
  import java.util.concurrent.ConcurrentLinkedDeque;
  import java.util.concurrent.Executor;
  import java.util.concurrent.ExecutorService;
  import java.util.concurrent.Executors;
  import java.util.concurrent.ThreadFactory;
  import java.util.concurrent.ThreadPoolExecutor;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.http.NoHttpResponseException;
  import org.apache.http.client.CredentialsProvider;
  import org.apache.http.cookie.MalformedCookieException;
  import org.htmlunit.attachment.Attachment;
  import org.htmlunit.attachment.AttachmentHandler;
  import org.htmlunit.csp.Policy;
  import org.htmlunit.csp.url.URI;
  import org.htmlunit.css.ComputedCssStyleDeclaration;
  import org.htmlunit.cssparser.parser.CSSErrorHandler;
  import org.htmlunit.cssparser.parser.javacc.CSS3Parser;
  import org.htmlunit.html.BaseFrameElement;
  import org.htmlunit.html.DomElement;
  import org.htmlunit.html.DomNode;
  import org.htmlunit.html.FrameWindow;
  import org.htmlunit.html.FrameWindow.PageDenied;
  import org.htmlunit.html.HtmlElement;
  import org.htmlunit.html.HtmlInlineFrame;
  import org.htmlunit.html.HtmlPage;
  import org.htmlunit.html.XHtmlPage;
  import org.htmlunit.html.parser.HTMLParser;
  import org.htmlunit.html.parser.HTMLParserListener;
  import org.htmlunit.http.HttpStatus;
  import org.htmlunit.http.HttpUtils;
  import org.htmlunit.httpclient.HttpClientConverter;
  import org.htmlunit.javascript.AbstractJavaScriptEngine;
  import org.htmlunit.javascript.DefaultJavaScriptErrorListener;
  import org.htmlunit.javascript.HtmlUnitScriptable;
  import org.htmlunit.javascript.JavaScriptEngine;
  import org.htmlunit.javascript.JavaScriptErrorListener;
  import org.htmlunit.javascript.background.JavaScriptJobManager;
  import org.htmlunit.javascript.host.BroadcastChannel;
  import org.htmlunit.javascript.host.Location;
  import org.htmlunit.javascript.host.Window;
  import org.htmlunit.javascript.host.dom.Node;
  import org.htmlunit.javascript.host.event.Event;
  import org.htmlunit.javascript.host.file.Blob;
  import org.htmlunit.javascript.host.html.HTMLIFrameElement;
  import org.htmlunit.protocol.data.DataURLConnection;
  import org.htmlunit.util.Cookie;
  import org.htmlunit.util.HeaderUtils;
  import org.htmlunit.util.MimeType;
 import org.htmlunit.util.NameValuePair;
 import org.htmlunit.util.StringUtils;
 import org.htmlunit.util.UrlUtils;
 import org.htmlunit.websocket.JettyWebSocketAdapter.JettyWebSocketAdapterFactory;
 import org.htmlunit.websocket.WebSocketAdapter;
 import org.htmlunit.websocket.WebSocketAdapterFactory;
 import org.htmlunit.websocket.WebSocketListener;
 import org.htmlunit.webstart.WebStartHandler;
 
 /**
  * The main starting point in HtmlUnit: this class simulates a web browser.
  * <p>
  * A standard usage of HtmlUnit will start with using the {@link #getPage(String)} method
  * (or {@link #getPage(URL)}) to load a first {@link Page}
  * and will continue with further processing on this page depending on its type.
  * </p>
  * <b>Example:</b><br>
  * <br>
  * <code>
  * final WebClient webClient = new WebClient();<br>
  * final {@link HtmlPage} startPage = webClient.getPage("http://htmlunit.sf.net");<br>
  * assertEquals("HtmlUnit - Welcome to HtmlUnit", startPage.{@link HtmlPage#getTitleText() getTitleText}());
  * </code>
  * <p>
  * Note: a {@link WebClient} instance is <b>not thread safe</b>. It is intended to be used from a single thread.
  * </p>
  * @author Mike Bowler
  * @author Mike J. Bresnahan
  * @author Dominique Broeglin
  * @author Noboru Sinohara
  * @author Chen Jun
  * @author David K. Taylor
  * @author Christian Sell
  * @author Ben Curren
  * @author Marc Guillemot
  * @author Chris Erskine
  * @author Daniel Gredler
  * @author Sergey Gorelkin
  * @author Hans Donner
  * @author Paul King
  * @author Ahmed Ashour
  * @author Bruce Chapman
  * @author Sudhan Moghe
  * @author Martin Tamme
  * @author Amit Manjhi
  * @author Nicolas Belisle
  * @author Ronald Brill
  * @author Frank Danek
  * @author Joerg Werner
  * @author Anton Demydenko
  * @author Sergio Moreno
  * @author Lai Quang Duong
  * @author René Schwietzke
  * @author Sven Strickroth
  */
 @SuppressWarnings("PMD.TooManyFields")
 public class WebClient implements Serializable, AutoCloseable {
 
     /** Logging support. */
     private static final Log LOG = LogFactory.getLog(WebClient.class);
 
     /** Like the Firefox default value for {@code network.http.redirection-limit}. */
     private static final int ALLOWED_REDIRECTIONS_SAME_URL = 20;
     private static final WebResponseData RESPONSE_DATA_NO_HTTP_RESPONSE = new WebResponseData(
             0, "No HTTP Response", Collections.emptyList());
 
     /**
      * These response headers are not copied from a 304 response to the cached
      * response headers. This list is based on Chromium http_response_headers.cc
      */
     private static final String[] DISCARDING_304_RESPONSE_HEADER_NAMES = {
         "connection",
         "proxy-connection",
         "keep-alive",
         "www-authenticate",
         "proxy-authenticate",
         "proxy-authorization",
         "te",
         "trailer",
         "transfer-encoding",
         "upgrade",
         "content-location",
         "content-md5",
         "etag",
         "content-encoding",
         "content-range",
         "content-type",
         "content-length",
         "x-frame-options",
         "x-xss-protection",
     };
 
     private static final String[] DISCARDING_304_HEADER_PREFIXES = {
         "x-content-",
         "x-webkit-"
     };
 
     private transient WebConnection webConnection_;
     private CredentialsProvider credentialsProvider_ = new DefaultCredentialsProvider();
     private CookieManager cookieManager_ = new CookieManager();
     private WebSocketAdapterFactory webSocketAdapterFactory_;
     private transient AbstractJavaScriptEngine<?> scriptEngine_;
     private transient List<LoadJob> loadQueue_;
     private final Map<String, String> requestHeaders_ = Collections.synchronizedMap(new HashMap<>(89));
     private IncorrectnessListener incorrectnessListener_ = new IncorrectnessListenerImpl();
     private WebConsole webConsole_;
     private transient ExecutorService executor_;
 
     private AlertHandler alertHandler_;
     private ConfirmHandler confirmHandler_;
     private PromptHandler promptHandler_;
     private StatusHandler statusHandler_;
     private AttachmentHandler attachmentHandler_;
     private ClipboardHandler clipboardHandler_;
     private PrintHandler printHandler_;
     private WebStartHandler webStartHandler_;
     private FrameContentHandler frameContentHandler_;
 
     private AjaxController ajaxController_ = new AjaxController();
 
     private final BrowserVersion browserVersion_;
     private PageCreator pageCreator_ = new DefaultPageCreator();
 
     // we need a separate one to be sure the one is always informed as first
     // one. Only then we can make sure our state is consistent when the others
     // are informed.
     private CurrentWindowTracker currentWindowTracker_;
     private final Set<WebWindowListener> webWindowListeners_ = new HashSet<>(5);
 
     private final List<TopLevelWindow> topLevelWindows_ =
             Collections.synchronizedList(new ArrayList<>()); // top-level windows
     private final List<WebWindow> windows_ = Collections.synchronizedList(new ArrayList<>()); // all windows
     private transient List<WeakReference<JavaScriptJobManager>> jobManagers_ =
             Collections.synchronizedList(new ArrayList<>());
     private WebWindow currentWindow_;
 
     private HTMLParserListener htmlParserListener_;
     private CSSErrorHandler cssErrorHandler_ = new DefaultCssErrorHandler();
     private OnbeforeunloadHandler onbeforeunloadHandler_;
     private Cache cache_ = new Cache();
 
     // mini pool to save resource when parsing CSS
     private transient CSS3ParserPool css3ParserPool_ = new CSS3ParserPool();
 
     /** target "_blank". */
     public static final String TARGET_BLANK = "_blank";
 
     /** target "_self". */
     public static final String TARGET_SELF = "_self";
 
     /** target "_parent". */
     private static final String TARGET_PARENT = "_parent";
     /** target "_top". */
     private static final String TARGET_TOP = "_top";
 
     private ScriptPreProcessor scriptPreProcessor_;
 
     private RefreshHandler refreshHandler_ = new NiceRefreshHandler(2);
     private JavaScriptErrorListener javaScriptErrorListener_ = new DefaultJavaScriptErrorListener();
 
     private final WebClientOptions options_ = new WebClientOptions();
     private final boolean javaScriptEngineEnabled_;
     private final StorageHolder storageHolder_ = new StorageHolder();
 
     private transient Set<BroadcastChannel> broadcastChannel_ = new HashSet<>();
 
     /**
      * Creates a web client instance using the browser version returned by
      * {@link BrowserVersion#getDefault()}.
      */
     public WebClient() {
         this(BrowserVersion.getDefault());
     }
 
     /**
      * Creates a web client instance using the specified {@link BrowserVersion}.
      * @param browserVersion the browser version to simulate
      */
     public WebClient(final BrowserVersion browserVersion) {
         this(browserVersion, null, -1);
     }
 
     /**
      * Creates an instance that will use the specified {@link BrowserVersion} and proxy server.
      * @param browserVersion the browser version to simulate
      * @param proxyHost the server that will act as proxy or null for no proxy
      * @param proxyPort the port to use on the proxy server
      */
     public WebClient(final BrowserVersion browserVersion, final String proxyHost, final int proxyPort) {
         this(browserVersion, true, proxyHost, proxyPort, null);
     }
 
     /**
      * Creates an instance that will use the specified {@link BrowserVersion} and proxy server.
      * @param browserVersion the browser version to simulate
      * @param proxyHost the server that will act as proxy or null for no proxy
      * @param proxyPort the port to use on the proxy server
      * @param proxyScheme the scheme http/https
      */
     public WebClient(final BrowserVersion browserVersion,
             final String proxyHost, final int proxyPort, final String proxyScheme) {
         this(browserVersion, true, proxyHost, proxyPort, proxyScheme);
     }
 
     /**
      * Creates an instance that will use the specified {@link BrowserVersion} and proxy server.
      * @param browserVersion the browser version to simulate
      * @param javaScriptEngineEnabled set to false if the simulated browser should not support javaScript
      * @param proxyHost the server that will act as proxy or null for no proxy
      * @param proxyPort the port to use on the proxy server
      */
     public WebClient(final BrowserVersion browserVersion, final boolean javaScriptEngineEnabled,
             final String proxyHost, final int proxyPort) {
         this(browserVersion, javaScriptEngineEnabled, proxyHost, proxyPort, null);
     }
 
     /**
      * Creates an instance that will use the specified {@link BrowserVersion} and proxy server.
      * @param browserVersion the browser version to simulate
      * @param javaScriptEngineEnabled set to false if the simulated browser should not support javaScript
      * @param proxyHost the server that will act as proxy or null for no proxy
      * @param proxyPort the port to use on the proxy server
      * @param proxyScheme the scheme http/https
      */
     public WebClient(final BrowserVersion browserVersion, final boolean javaScriptEngineEnabled,
             final String proxyHost, final int proxyPort, final String proxyScheme) {
         WebAssert.notNull("browserVersion", browserVersion);
 
         browserVersion_ = browserVersion;
         javaScriptEngineEnabled_ = javaScriptEngineEnabled;
 
         if (proxyHost == null) {
             getOptions().setProxyConfig(new ProxyConfig());
         }
         else {
             getOptions().setProxyConfig(new ProxyConfig(proxyHost, proxyPort, proxyScheme));
         }
 
         webConnection_ = new HttpWebConnection(this); // this has to be done after the browser version was set
         if (javaScriptEngineEnabled_) {
             scriptEngine_ = new JavaScriptEngine(this);
         }
         loadQueue_ = new ArrayList<>();
 
         webSocketAdapterFactory_ = new JettyWebSocketAdapterFactory();
 
         // The window must be constructed AFTER the script engine.
         currentWindowTracker_ = new CurrentWindowTracker(this, true);
         currentWindow_ = new TopLevelWindow("", this);
     }
 
     /**
      * Our simple impl of a ThreadFactory (decorator) to be able to name
      * our threads.
      */
     private static final class ThreadNamingFactory implements ThreadFactory {
         private static int ID_ = 1;
         private final ThreadFactory baseFactory_;
 
         ThreadNamingFactory(final ThreadFactory aBaseFactory) {
             baseFactory_ = aBaseFactory;
         }
 
         @Override
         public Thread newThread(final Runnable aRunnable) {
             final Thread thread = baseFactory_.newThread(aRunnable);
             thread.setName("WebClient Thread " + ID_++);
             return thread;
         }
     }
 
     /**
      * Returns the object that will resolve all URL requests.
      *
      * @return the connection that will be used
      */
     public WebConnection getWebConnection() {
         return webConnection_;
     }
 
     /**
      * Sets the object that will resolve all URL requests.
      *
      * @param webConnection the new web connection
      */
     public void setWebConnection(final WebConnection webConnection) {
         WebAssert.notNull("webConnection", webConnection);
         webConnection_ = webConnection;
     }
 
     /**
      * Send a request to a server and return a Page that represents the
      * response from the server. This page will be used to populate the provided window.
      * <p>
      * The returned {@link Page} will be created by the {@link PageCreator}
      * configured by {@link #setPageCreator(PageCreator)}, if any.
      * <p>
      * The {@link DefaultPageCreator} will create a {@link Page} depending on the content type of the HTTP response,
      * basically {@link HtmlPage} for HTML content, {@link org.htmlunit.xml.XmlPage} for XML content,
      * {@link TextPage} for other text content and {@link UnexpectedPage} for anything else.
      *
      * @param webWindow the WebWindow to load the result of the request into
      * @param webRequest the web request
      * @param <P> the page type
      * @return the page returned by the server when the specified request was made in the specified window
      * @throws IOException if an IO error occurs
      * @throws FailingHttpStatusCodeException if the server returns a failing status code AND the property
      *         {@link WebClientOptions#setThrowExceptionOnFailingStatusCode(boolean)} is set to true
      *
      * @see WebRequest
      */
     public <P extends Page> P getPage(final WebWindow webWindow, final WebRequest webRequest)
             throws IOException, FailingHttpStatusCodeException {
         return getPage(webWindow, webRequest, true);
     }
 
     /**
      * <span style="color:red">INTERNAL API - SUBJECT TO CHANGE AT ANY TIME - USE AT YOUR OWN RISK.</span><br>
      *
      * Send a request to a server and return a Page that represents the
      * response from the server. This page will be used to populate the provided window.
      * <p>
      * The returned {@link Page} will be created by the {@link PageCreator}
      * configured by {@link #setPageCreator(PageCreator)}, if any.
      * <p>
      * The {@link DefaultPageCreator} will create a {@link Page} depending on the content type of the HTTP response,
      * basically {@link HtmlPage} for HTML content, {@link org.htmlunit.xml.XmlPage} for XML content,
      * {@link TextPage} for other text content and {@link UnexpectedPage} for anything else.
      *
      * @param webWindow the WebWindow to load the result of the request into
      * @param webRequest the web request
      * @param addToHistory true if the page should be part of the history
      * @param <P> the page type
      * @return the page returned by the server when the specified request was made in the specified window
      * @throws IOException if an IO error occurs
      * @throws FailingHttpStatusCodeException if the server returns a failing status code AND the property
      *         {@link WebClientOptions#setThrowExceptionOnFailingStatusCode(boolean)} is set to true
      *
      * @see WebRequest
      */
     @SuppressWarnings("unchecked")
     <P extends Page> P getPage(final WebWindow webWindow, final WebRequest webRequest,
             final boolean addToHistory)
         throws IOException, FailingHttpStatusCodeException {
 
         final Page page = webWindow.getEnclosedPage();
 
         if (page != null) {
             final URL prev = page.getUrl();
             final URL current = webRequest.getUrl();
             if (UrlUtils.sameFile(current, prev)
                         && current.getRef() != null
                         && !Objects.equals(current.getRef(), prev.getRef())) {
                 // We're just navigating to an anchor within the current page.
                 page.getWebResponse().getWebRequest().setUrl(current);
                 if (addToHistory) {
                     webWindow.getHistory().addPage(page);
                 }
 
                 // clear the cache because the anchors are now matched by
                 // the target pseudo style
                 if (page instanceof HtmlPage) {
                     ((HtmlPage) page).clearComputedStyles();
                 }
 
                 final Window window = webWindow.getScriptableObject();
                 if (window != null) { // js enabled
                     window.getLocation().setHash(current.getRef());
                 }
                 return (P) page;
             }
 
             if (page.isHtmlPage()) {
                 final HtmlPage htmlPage = (HtmlPage) page;
                 if (!htmlPage.isOnbeforeunloadAccepted()) {
                     LOG.debug("The registered OnbeforeunloadHandler rejected to load a new page.");
                     return (P) page;
                 }
             }
         }
 
         if (LOG.isDebugEnabled()) {
             LOG.debug("Get page for window named '" + webWindow.getName() + "', using " + webRequest);
         }
 
         WebResponse webResponse;
         final String protocol = webRequest.getUrl().getProtocol();
         if ("javascript".equals(protocol)) {
             webResponse = makeWebResponseForJavaScriptUrl(webWindow, webRequest.getUrl(), webRequest.getCharset());
             if (webWindow.getEnclosedPage() != null && webWindow.getEnclosedPage().getWebResponse() == webResponse) {
                 // a javascript:... url with result of type undefined didn't changed the page
                 return (P) webWindow.getEnclosedPage();
             }
         }
         else {
             try {
                 webResponse = loadWebResponse(webRequest);
             }
             catch (final NoHttpResponseException e) {
                 webResponse = new WebResponse(RESPONSE_DATA_NO_HTTP_RESPONSE, webRequest, 0);
             }
         }
 
         printContentIfNecessary(webResponse);
         loadWebResponseInto(webResponse, webWindow);
 
         // start execution here
         // note: we have to do this also if the server reports an error!
         //       e.g. if the server returns a 404 error page that includes javascript
         if (scriptEngine_ != null) {
             scriptEngine_.registerWindowAndMaybeStartEventLoop(webWindow);
         }
 
         // check and report problems if needed
         throwFailingHttpStatusCodeExceptionIfNecessary(webResponse);
         return (P) webWindow.getEnclosedPage();
     }
 
     /**
      * Convenient method to build a URL and load it into the current WebWindow as it would be done
      * by {@link #getPage(WebWindow, WebRequest)}.
      * @param url the URL of the new content; in contrast to real browsers plain file url's are not supported.
      *        You have to use the 'file', 'data', 'blob', 'http' or 'https' protocol.
      * @param <P> the page type
      * @return the new page
      * @throws FailingHttpStatusCodeException if the server returns a failing status code AND the property
      *         {@link WebClientOptions#setThrowExceptionOnFailingStatusCode(boolean)} is set to true.
      * @throws IOException if an IO problem occurs
      * @throws MalformedURLException if no URL can be created from the provided string
      */
     public <P extends Page> P getPage(final String url) throws IOException, FailingHttpStatusCodeException,
         MalformedURLException {
         return getPage(UrlUtils.toUrlUnsafe(url));
     }
 
     /**
      * Convenient method to load a URL into the current top WebWindow as it would be done
      * by {@link #getPage(WebWindow, WebRequest)}.
      * @param url the URL of the new content; in contrast to real browsers plain file url's are not supported.
      *        You have to use the 'file', 'data', 'blob', 'http' or 'https' protocol.
      * @param <P> the page type
      * @return the new page
      * @throws FailingHttpStatusCodeException if the server returns a failing status code AND the property
      *         {@link WebClientOptions#setThrowExceptionOnFailingStatusCode(boolean)} is set to true.
      * @throws IOException if an IO problem occurs
      */
     public <P extends Page> P getPage(final URL url) throws IOException, FailingHttpStatusCodeException {
         final WebRequest request = new WebRequest(url, getBrowserVersion().getHtmlAcceptHeader(),
                                                           getBrowserVersion().getAcceptEncodingHeader());
         request.setCharset(UTF_8);
         return getPage(getCurrentWindow().getTopWindow(), request);
     }
 
     /**
      * Convenient method to load a web request into the current top WebWindow.
      * @param request the request parameters
      * @param <P> the page type
      * @return the new page
      * @throws FailingHttpStatusCodeException if the server returns a failing status code AND the property
      *         {@link WebClientOptions#setThrowExceptionOnFailingStatusCode(boolean)} is set to true.
      * @throws IOException if an IO problem occurs
      * @see #getPage(WebWindow,WebRequest)
      */
     public <P extends Page> P getPage(final WebRequest request) throws IOException,
         FailingHttpStatusCodeException {
         return getPage(getCurrentWindow().getTopWindow(), request);
     }
 
     /**
      * <p>Creates a page based on the specified response and inserts it into the specified window. All page
      * initialization and event notification is handled here.</p>
      *
      * <p>Note that if the page created is an attachment page, and an {@link AttachmentHandler} has been
      * registered with this client, the page is <b>not</b> loaded into the specified window; in this case,
      * the page is loaded into a new window, and attachment handling is delegated to the registered
      * <code>AttachmentHandler</code>.</p>
      *
      * @param webResponse the response that will be used to create the new page
      * @param webWindow the window that the new page will be placed within
      * @throws IOException if an IO error occurs
      * @throws FailingHttpStatusCodeException if the server returns a failing status code AND the property
      *         {@link WebClientOptions#setThrowExceptionOnFailingStatusCode(boolean)} is set to true
      * @return the newly created page
      * @see #setAttachmentHandler(AttachmentHandler)
      */
     public Page loadWebResponseInto(final WebResponse webResponse, final WebWindow webWindow)
         throws IOException, FailingHttpStatusCodeException {
         return loadWebResponseInto(webResponse, webWindow, null);
     }
 
     /**
      * <span style="color:red">INTERNAL API - SUBJECT TO CHANGE AT ANY TIME - USE AT YOUR OWN RISK.</span><br>
      *
      * <p>Creates a page based on the specified response and inserts it into the specified window. All page
      * initialization and event notification is handled here.</p>
      *
      * <p>Note that if the page created is an attachment page, and an {@link AttachmentHandler} has been
      * registered with this client, the page is <b>not</b> loaded into the specified window; in this case,
      * the page is loaded into a new window, and attachment handling is delegated to the registered
      * <code>AttachmentHandler</code>.</p>
      *
      * @param webResponse the response that will be used to create the new page
      * @param webWindow the window that the new page will be placed within
      * @param forceAttachmentWithFilename if not {@code null}, handle this as an attachment with the specified name
      *        or if an empty string ("") use the filename provided in the response
      * @throws IOException if an IO error occurs
      * @throws FailingHttpStatusCodeException if the server returns a failing status code AND the property
      *         {@link WebClientOptions#setThrowExceptionOnFailingStatusCode(boolean)} is set to true
      * @return the newly created page
      * @see #setAttachmentHandler(AttachmentHandler)
      */
     public Page loadWebResponseInto(final WebResponse webResponse, final WebWindow webWindow,
             String forceAttachmentWithFilename)
             throws IOException, FailingHttpStatusCodeException {
         WebAssert.notNull("webResponse", webResponse);
         WebAssert.notNull("webWindow", webWindow);
 
         if (webResponse.getStatusCode() == HttpStatus.NO_CONTENT_204) {
             return webWindow.getEnclosedPage();
         }
 
         if (webStartHandler_ != null && "application/x-java-jnlp-file".equals(webResponse.getContentType())) {
             webStartHandler_.handleJnlpResponse(webResponse);
             return webWindow.getEnclosedPage();
         }
 
         if (attachmentHandler_ != null
                 && (forceAttachmentWithFilename != null || attachmentHandler_.isAttachment(webResponse))) {
 
             // check content disposition header for nothing provided
             if (StringUtils.isEmptyOrNull(forceAttachmentWithFilename)) {
                 final String disp = webResponse.getResponseHeaderValue(HttpHeader.CONTENT_DISPOSITION);
                 forceAttachmentWithFilename = Attachment.getSuggestedFilename(disp);
             }
 
             if (attachmentHandler_.handleAttachment(webResponse,
                         StringUtils.isEmptyOrNull(forceAttachmentWithFilename) ? null : forceAttachmentWithFilename)) {
                 // the handling is done by the attachment handler;
                 // do not open a new window
                 return webWindow.getEnclosedPage();
             }
 
             final WebWindow w = openWindow(null, null, webWindow);
             final Page page = pageCreator_.createPage(webResponse, w);
             attachmentHandler_.handleAttachment(page,
                                 StringUtils.isEmptyOrNull(forceAttachmentWithFilename)
                                         ? null : forceAttachmentWithFilename);
             return page;
         }
 
         final Page oldPage = webWindow.getEnclosedPage();
         if (oldPage != null) {
             // Remove the old page before create new one.
             oldPage.cleanUp();
         }
 
         Page newPage = null;
         FrameWindow.PageDenied pageDenied = PageDenied.NONE;
         if (windows_.contains(webWindow)) {
             if (webWindow instanceof FrameWindow) {
                 final String contentSecurityPolicy =
                         webResponse.getResponseHeaderValue(HttpHeader.CONTENT_SECURIRY_POLICY);
                 if (StringUtils.isNotBlank(contentSecurityPolicy)) {
                     final URL origin = UrlUtils.getUrlWithoutPathRefQuery(
                             ((FrameWindow) webWindow).getEnclosingPage().getUrl());
                     final URL source = UrlUtils.getUrlWithoutPathRefQuery(webResponse.getWebRequest().getUrl());
                     final Policy policy = Policy.parseSerializedCSP(contentSecurityPolicy,
                                                     Policy.PolicyErrorConsumer.ignored);
                     if (!policy.allowsFrameAncestor(
                             Optional.of(URI.parseURI(source.toExternalForm()).orElse(null)),
                             Optional.of(URI.parseURI(origin.toExternalForm()).orElse(null)))) {
                         pageDenied = PageDenied.BY_CONTENT_SECURIRY_POLICY;
 
                         if (LOG.isWarnEnabled()) {
                             LOG.warn("Load denied by Content-Security-Policy: '" + contentSecurityPolicy + "' - "
                                     + webResponse.getWebRequest().getUrl() + "' does not permit framing.");
                         }
                     }
                 }
 
                 if (pageDenied == PageDenied.NONE) {
                     final String xFrameOptions = webResponse.getResponseHeaderValue(HttpHeader.X_FRAME_OPTIONS);
                     if ("DENY".equalsIgnoreCase(xFrameOptions)) {
                         pageDenied = PageDenied.BY_X_FRAME_OPTIONS;
 
                         if (LOG.isWarnEnabled()) {
                             LOG.warn("Load denied by X-Frame-Options: DENY; - '"
                                     + webResponse.getWebRequest().getUrl() + "' does not permit framing.");
                         }
                     }
                 }
             }
 
             if (pageDenied == PageDenied.NONE) {
                 newPage = pageCreator_.createPage(webResponse, webWindow);
             }
             else {
                 try {
                     final WebResponse aboutBlank = loadWebResponse(WebRequest.newAboutBlankRequest());
                     newPage = pageCreator_.createPage(aboutBlank, webWindow);
                     // TODO - maybe we have to attach to original request/response to the page
 
                     ((FrameWindow) webWindow).setPageDenied(pageDenied);
                 }
                 catch (final IOException ignored) {
                     // ignore
                 }
             }
 
             if (windows_.contains(webWindow)) {
                 fireWindowContentChanged(new WebWindowEvent(webWindow, WebWindowEvent.CHANGE, oldPage, newPage));
 
                 // The page being loaded may already have been replaced by another page via JavaScript code.
                 if (webWindow.getEnclosedPage() == newPage) {
                     newPage.initialize();
                     // hack: onload should be fired the same way for all type of pages
                     // here is a hack to handle non HTML pages
                     if (isJavaScriptEnabled()
                             && webWindow instanceof FrameWindow && !newPage.isHtmlPage()) {
                         final FrameWindow fw = (FrameWindow) webWindow;
                         final BaseFrameElement frame = fw.getFrameElement();
                         if (frame.hasEventHandlers("onload")) {
                             if (LOG.isDebugEnabled()) {
                                 LOG.debug("Executing onload handler for " + frame);
                             }
                             final Event event = new Event(frame, Event.TYPE_LOAD);
                             ((Node) frame.getScriptableObject()).executeEventLocally(event);
                         }
                     }
                 }
             }
         }
         return newPage;
     }
 
     /**
      * <span style="color:red">INTERNAL API - SUBJECT TO CHANGE AT ANY TIME - USE AT YOUR OWN RISK.</span>
      *
      * <p>Logs the response's content if its status code indicates a request failure and
      * {@link WebClientOptions#isPrintContentOnFailingStatusCode()} returns {@code true}.
      *
      * @param webResponse the response whose content may be logged
      */
     public void printContentIfNecessary(final WebResponse webResponse) {
         if (getOptions().isPrintContentOnFailingStatusCode()
                 && !webResponse.isSuccess() && LOG.isInfoEnabled()) {
             final String contentType = webResponse.getContentType();
             LOG.info("statusCode=[" + webResponse.getStatusCode() + "] contentType=[" + contentType + "]");
             LOG.info(webResponse.getContentAsString());
         }
     }
 
     /**
      * <span style="color:red">INTERNAL API - SUBJECT TO CHANGE AT ANY TIME - USE AT YOUR OWN RISK.</span>
      *
      * <p>Throws a {@link FailingHttpStatusCodeException} if the request's status code indicates a request
      * failure and {@link WebClientOptions#isThrowExceptionOnFailingStatusCode()} returns {@code true}.
      *
      * @param webResponse the response which may trigger a {@link FailingHttpStatusCodeException}
      */
     public void throwFailingHttpStatusCodeExceptionIfNecessary(final WebResponse webResponse) {
         if (getOptions().isThrowExceptionOnFailingStatusCode() && !webResponse.isSuccessOrUseProxyOrNotModified()) {
             throw new FailingHttpStatusCodeException(webResponse);
         }
     }
 
     /**
      * Adds a header which will be sent with EVERY request from this client.
      * This list is empty per default; use this to add specific headers for your
      * case.
      * @param name the name of the header to add
      * @param value the value of the header to add
      * @see #removeRequestHeader(String)
      */
     public void addRequestHeader(final String name, final String value) {
         if (HttpHeader.COOKIE_LC.equalsIgnoreCase(name)) {
             throw new IllegalArgumentException("Do not add 'Cookie' header, use .getCookieManager() instead");
         }
         requestHeaders_.put(name, value);
     }
 
     /**
      * Removes a header from being sent with EVERY request from this client.
      * This list is empty per default; use this method to remove specific headers
      * your have added using {{@link #addRequestHeader(String, String)} before.<br>
      * You can't use this to avoid sending standard headers like "Accept-Language"
      * or "Sec-Fetch-Dest".
      * @param name the name of the header to remove
      * @see #addRequestHeader
      */
     public void removeRequestHeader(final String name) {
         requestHeaders_.remove(name);
     }
 
     /**
      * Sets the credentials provider that will provide authentication information when
      * trying to access protected information on a web server. This information is
      * required when the server is using Basic HTTP authentication, NTLM authentication,
      * or Digest authentication.
      * @param credentialsProvider the new credentials provider to use to authenticate
      */
     public void setCredentialsProvider(final CredentialsProvider credentialsProvider) {
         WebAssert.notNull("credentialsProvider", credentialsProvider);
         credentialsProvider_ = credentialsProvider;
     }
 
     /**
      * Returns the credentials provider for this client instance. By default, this
      * method returns an instance of {@link DefaultCredentialsProvider}.
      * @return the credentials provider for this client instance
      */
     public CredentialsProvider getCredentialsProvider() {
         return credentialsProvider_;
     }
 
     /**
      * This method is intended for testing only - use at your own risk.
      * @return the current JavaScript engine (never {@code null})
      */
     public AbstractJavaScriptEngine<?> getJavaScriptEngine() {
         return scriptEngine_;
     }
 
     /**
      * This method is intended for testing only - use at your own risk.
      *
      * @param engine the new script engine to use
      */
     public void setJavaScriptEngine(final AbstractJavaScriptEngine<?> engine) {
         if (engine == null) {
             throw new IllegalArgumentException("Can't set JavaScriptEngine to null");
         }
         scriptEngine_ = engine;
     }
 
     /**
      * Returns the cookie manager used by this web client.
      * @return the cookie manager used by this web client
      */
     public CookieManager getCookieManager() {
         return cookieManager_;
     }
 
     /**
      * Sets the cookie manager used by this web client.
      * @param cookieManager the cookie manager used by this web client
      */
     public void setCookieManager(final CookieManager cookieManager) {
         WebAssert.notNull("cookieManager", cookieManager);
         cookieManager_ = cookieManager;
     }
 
     /**
      * Sets the alert handler for this webclient.
      * @param alertHandler the new alerthandler or null if none is specified
      */
     public void setAlertHandler(final AlertHandler alertHandler) {
         alertHandler_ = alertHandler;
     }
 
     /**
      * Returns the alert handler for this webclient.
      * @return the alert handler or null if one hasn't been set
      */
     public AlertHandler getAlertHandler() {
         return alertHandler_;
     }
 
     /**
      * Sets the handler that will be executed when the JavaScript method Window.confirm() is called.
      * @param handler the new handler or null if no handler is to be used
      */
     public void setConfirmHandler(final ConfirmHandler handler) {
         confirmHandler_ = handler;
     }
 
     /**
      * Returns the confirm handler.
      * @return the confirm handler or null if one hasn't been set
      */
     public ConfirmHandler getConfirmHandler() {
         return confirmHandler_;
     }
 
     /**
      * Sets the handler that will be executed when the JavaScript method Window.prompt() is called.
      * @param handler the new handler or null if no handler is to be used
      */
     public void setPromptHandler(final PromptHandler handler) {
         promptHandler_ = handler;
     }
 
     /**
      * Returns the prompt handler.
      * @return the prompt handler or null if one hasn't been set
      */
     public PromptHandler getPromptHandler() {
         return promptHandler_;
     }
 
     /**
      * Sets the status handler for this webclient.
      * @param statusHandler the new status handler or null if none is specified
      */
     public void setStatusHandler(final StatusHandler statusHandler) {
         statusHandler_ = statusHandler;
     }
 
     /**
      * Returns the status handler for this {@link WebClient}.
      * @return the status handler or null if one hasn't been set
      */
     public StatusHandler getStatusHandler() {
         return statusHandler_;
     }
 
     /**
      * Returns the executor for this {@link WebClient}.
      * @return the executor
      */
     public synchronized Executor getExecutor() {
         if (executor_ == null) {
             final ThreadPoolExecutor threadPoolExecutor = (ThreadPoolExecutor) Executors.newCachedThreadPool();
             threadPoolExecutor.setThreadFactory(new ThreadNamingFactory(threadPoolExecutor.getThreadFactory()));
             // threadPoolExecutor.prestartAllCoreThreads();
             executor_ = threadPoolExecutor;
         }
 
         return executor_;
     }
 
     /**
      * Changes the ExecutorService for this {@link WebClient}.
      * You have to call this before the first use of the executor, otherwise
      * an IllegalStateExceptions is thrown.
      * @param executor the new Executor.
      */
     public synchronized void setExecutor(final ExecutorService executor) {
         if (executor_ != null) {
             throw new IllegalStateException("Can't change the executor after first use.");
         }
 
         executor_ = executor;
     }
 
     /**
      * Sets the javascript error listener for this {@link WebClient}.
      * When setting to null, the {@link DefaultJavaScriptErrorListener} is used.
      * @param javaScriptErrorListener the new JavaScriptErrorListener or null if none is specified
      */
     public void setJavaScriptErrorListener(final JavaScriptErrorListener javaScriptErrorListener) {
         if (javaScriptErrorListener == null) {
             javaScriptErrorListener_ = new DefaultJavaScriptErrorListener();
         }
         else {
             javaScriptErrorListener_ = javaScriptErrorListener;
         }
     }
 
     /**
      * Returns the javascript error listener for this {@link WebClient}.
      * @return the javascript error listener or null if one hasn't been set
      */
     public JavaScriptErrorListener getJavaScriptErrorListener() {
         return javaScriptErrorListener_;
     }
 
     /**
      * Returns the current browser version.
      * @return the current browser version
      */
     public BrowserVersion getBrowserVersion() {
         return browserVersion_;
     }
 
     /**
      * Returns the "current" window for this client. This window (or its top window) will be used
      * when <code>getPage(...)</code> is called without specifying a window.
      * @return the "current" window for this client
      */
     public WebWindow getCurrentWindow() {
         return currentWindow_;
     }
 
     /**
      * Sets the "current" window for this client. This is the window that will be used when
      * <code>getPage(...)</code> is called without specifying a window.
      * @param window the new "current" window for this client
      */
     public void setCurrentWindow(final WebWindow window) {
         WebAssert.notNull("window", window);
         if (currentWindow_ == window) {
             return;
         }
         // onBlur event is triggered for focused element of old current window
         if (currentWindow_ != null && !currentWindow_.isClosed()) {
             final Page enclosedPage = currentWindow_.getEnclosedPage();
             if (enclosedPage != null && enclosedPage.isHtmlPage()) {
                 final DomElement focusedElement = ((HtmlPage) enclosedPage).getFocusedElement();
                 if (focusedElement != null) {
                     focusedElement.fireEvent(Event.TYPE_BLUR);
                 }
             }
         }
         currentWindow_ = window;
 
         // when marking an iframe window as current we have no need to move the focus
         final boolean isIFrame = currentWindow_ instanceof FrameWindow
                 && ((FrameWindow) currentWindow_).getFrameElement() instanceof HtmlInlineFrame;
         if (!isIFrame) {
             //1. activeElement becomes focused element for new current window
             //2. onFocus event is triggered for focusedElement of new current window
             final Page enclosedPage = currentWindow_.getEnclosedPage();
             if (enclosedPage != null && enclosedPage.isHtmlPage()) {
                 final HtmlPage enclosedHtmlPage = (HtmlPage) enclosedPage;
                 final HtmlElement activeElement = enclosedHtmlPage.getActiveElement();
                 if (activeElement != null) {
                     enclosedHtmlPage.setFocusedElement(activeElement, true);
                 }
             }
         }
     }
 
     /**
      * Adds a listener for {@link WebWindowEvent}s. All events from all windows associated with this
      * client will be sent to the specified listener.
      * @param listener a listener
      */
     public void addWebWindowListener(final WebWindowListener listener) {
         WebAssert.notNull("listener", listener);
         webWindowListeners_.add(listener);
     }
 
     /**
      * Removes a listener for {@link WebWindowEvent}s.
      * @param listener a listener
      */
     public void removeWebWindowListener(final WebWindowListener listener) {
         WebAssert.notNull("listener", listener);
         webWindowListeners_.remove(listener);
     }
 
     private void fireWindowContentChanged(final WebWindowEvent event) {
         if (currentWindowTracker_ != null) {
             currentWindowTracker_.webWindowContentChanged(event);
         }
         for (final WebWindowListener listener : new ArrayList<>(webWindowListeners_)) {
             listener.webWindowContentChanged(event);
         }
     }
 
     private void fireWindowOpened(final WebWindowEvent event) {
         if (currentWindowTracker_ != null) {
             currentWindowTracker_.webWindowOpened(event);
         }
         for (final WebWindowListener listener : new ArrayList<>(webWindowListeners_)) {
             listener.webWindowOpened(event);
         }
     }
 
     private void fireWindowClosed(final WebWindowEvent event) {
         if (currentWindowTracker_ != null) {
             currentWindowTracker_.webWindowClosed(event);
         }
 
         for (final WebWindowListener listener : new ArrayList<>(webWindowListeners_)) {
             listener.webWindowClosed(event);
         }
 
         // to open a new top level window if all others are gone
         if (currentWindowTracker_ != null) {
             currentWindowTracker_.afterWebWindowClosedListenersProcessed(event);
         }
     }
 
     /**
      * Open a new window with the specified name. If the URL is non-null then attempt to load
      * a page from that location and put it in the new window.
      *
      * @param url the URL to load content from or null if no content is to be loaded
      * @param windowName the name of the new window
      * @return the new window
      */
     public WebWindow openWindow(final URL url, final String windowName) {
         WebAssert.notNull("windowName", windowName);
         return openWindow(url, windowName, getCurrentWindow());
     }
 
     /**
      * Open a new window with the specified name. If the URL is non-null then attempt to load
      * a page from that location and put it in the new window.
      *
      * @param url the URL to load content from or null if no content is to be loaded
      * @param windowName the name of the new window
      * @param opener the web window that is calling openWindow
      * @return the new window
      */
     public WebWindow openWindow(final URL url, final String windowName, final WebWindow opener) {
         final WebWindow window = openTargetWindow(opener, windowName, TARGET_BLANK);
         if (url == null) {
             initializeEmptyWindow(window, window.getEnclosedPage());
         }
         else {
             try {
                 final WebRequest request = new WebRequest(url, getBrowserVersion().getHtmlAcceptHeader(),
                                                                 getBrowserVersion().getAcceptEncodingHeader());
                 request.setCharset(UTF_8);
 
                 final Page openerPage = opener.getEnclosedPage();
                 if (openerPage != null && openerPage.getUrl() != null) {
                     request.setRefererHeader(openerPage.getUrl());
                 }
                 getPage(window, request);
             }
             catch (final IOException e) {
                 LOG.error("Error loading content into window", e);
             }
         }
         return window;
     }
 
     /**
      * <span style="color:red">INTERNAL API - SUBJECT TO CHANGE AT ANY TIME - USE AT YOUR OWN RISK.</span><br>
      *
      * Open the window with the specified name. The name may be a special
      * target name of _self, _parent, _top, or _blank. An empty or null
      * name is set to the default. The special target names are relative to
      * the opener window.
      *
      * @param opener the web window that is calling openWindow
      * @param windowName the name of the new window
      * @param defaultName the default target if no name is given
      * @return the new window
      */
     public WebWindow openTargetWindow(
             final WebWindow opener, final String windowName, final String defaultName) {
 
         WebAssert.notNull("opener", opener);
         WebAssert.notNull("defaultName", defaultName);
 
         String windowToOpen = windowName;
         if (windowToOpen == null || windowToOpen.isEmpty()) {
             windowToOpen = defaultName;
         }
 
         WebWindow webWindow = resolveWindow(opener, windowToOpen);
 
         if (webWindow == null) {
             if (TARGET_BLANK.equals(windowToOpen)) {
                 windowToOpen = "";
             }
             webWindow = new TopLevelWindow(windowToOpen, this);
         }
 
         if (webWindow instanceof TopLevelWindow && webWindow != opener.getTopWindow()) {
             ((TopLevelWindow) webWindow).setOpener(opener);
         }
 
         return webWindow;
     }
 
     private WebWindow resolveWindow(final WebWindow opener, final String name) {
         if (name == null || name.isEmpty() || TARGET_SELF.equals(name)) {
             return opener;
         }
 
         if (TARGET_PARENT.equals(name)) {
             return opener.getParentWindow();
         }
 
         if (TARGET_TOP.equals(name)) {
             return opener.getTopWindow();
         }
 
         if (TARGET_BLANK.equals(name)) {
             return null;
         }
 
         // first search for frame windows inside our window hierarchy
         WebWindow window = opener;
         while (true) {
             final Page page = window.getEnclosedPage();
             if (page != null && page.isHtmlPage()) {
                 try {
                     final FrameWindow frame = ((HtmlPage) page).getFrameByName(name);
                     final HtmlUnitScriptable scriptable = frame.getFrameElement().getScriptableObject();
                     if (scriptable instanceof HTMLIFrameElement) {
                         ((HTMLIFrameElement) scriptable).onRefresh();
                     }
                     return frame;
                 }
                 catch (final ElementNotFoundException expected) {
                     // Fall through
                 }
             }
 
             if (window == window.getParentWindow()) {
                 // TODO: should getParentWindow() return null on top windows?
                 break;
             }
             window = window.getParentWindow();
         }
 
         try {
             return getWebWindowByName(name);
         }
         catch (final WebWindowNotFoundException expected) {
             // Fall through - a new window will be created below
         }
         return null;
     }
 
     /**
      * <p><span style="color:red">INTERNAL API - SUBJECT TO CHANGE AT ANY TIME - USE AT YOUR OWN RISK.</span></p>
      *
      * Opens a new dialog window.
      * @param url the URL of the document to load and display
      * @param opener the web window that is opening the dialog
      * @param dialogArguments the object to make available inside the dialog via <code>window.dialogArguments</code>
      * @return the new dialog window
      * @throws IOException if there is an IO error
      */
     public DialogWindow openDialogWindow(final URL url, final WebWindow opener, final Object dialogArguments)
         throws IOException {
 
         WebAssert.notNull("url", url);
         WebAssert.notNull("opener", opener);
 
         final DialogWindow window = new DialogWindow(this, dialogArguments);
 
         final HtmlPage openerPage = (HtmlPage) opener.getEnclosedPage();
         final WebRequest request = new WebRequest(url, getBrowserVersion().getHtmlAcceptHeader(),
                                                         getBrowserVersion().getAcceptEncodingHeader());
         request.setCharset(UTF_8);
 
         if (openerPage != null) {
             request.setRefererHeader(openerPage.getUrl());
         }
 
         getPage(window, request);
 
         return window;
     }
 
     /**
      * Sets the object that will be used to create pages. Set this if you want
      * to customize the type of page that is returned for a given content type.
      *
      * @param pageCreator the new page creator
      */
     public void setPageCreator(final PageCreator pageCreator) {
         WebAssert.notNull("pageCreator", pageCreator);
         pageCreator_ = pageCreator;
     }
 
     /**
      * Returns the current page creator.
      *
      * @return the page creator
      */
     public PageCreator getPageCreator() {
         return pageCreator_;
     }
 
     /**
      * Returns the first {@link WebWindow} that matches the specified name.
      *
      * @param name the name to search for
      * @return the {@link WebWindow} with the specified name
      * @throws WebWindowNotFoundException if the {@link WebWindow} can't be found
      * @see #getWebWindows()
      * @see #getTopLevelWindows()
      */
     public WebWindow getWebWindowByName(final String name) throws WebWindowNotFoundException {
         WebAssert.notNull("name", name);
 
         for (final WebWindow webWindow : windows_) {
             if (name.equals(webWindow.getName())) {
                 return webWindow;
             }
         }
 
         throw new WebWindowNotFoundException(name);
     }
 
     /**
      * <span style="color:red">INTERNAL API - SUBJECT TO CHANGE AT ANY TIME - USE AT YOUR OWN RISK.</span><br>
      *
      * Initializes a new web window for JavaScript.
      * @param webWindow the new WebWindow
      * @param page the page that will become the enclosing page
      */
     public void initialize(final WebWindow webWindow, final Page page) {
         WebAssert.notNull("webWindow", webWindow);
 
         if (isJavaScriptEngineEnabled()) {
             scriptEngine_.initialize(webWindow, page);
         }
     }
 
     /**
      * <span style="color:red">INTERNAL API - SUBJECT TO CHANGE AT ANY TIME - USE AT YOUR OWN RISK.</span><br>
      *
      * Initializes a new empty window for JavaScript.
      *
      * @param webWindow the new WebWindow
      * @param page the page that will become the enclosing page
      */
     public void initializeEmptyWindow(final WebWindow webWindow, final Page page) {
         WebAssert.notNull("webWindow", webWindow);
 
         if (isJavaScriptEngineEnabled()) {
             initialize(webWindow, page);
             ((Window) webWindow.getScriptableObject()).initialize();
         }
     }
 
     /**
      * <span style="color:red">INTERNAL API - SUBJECT TO CHANGE AT ANY TIME - USE AT YOUR OWN RISK.</span><br>
      *
      * Adds a new window to the list of available windows.
      *
      * @param webWindow the new WebWindow
      */
     public void registerWebWindow(final WebWindow webWindow) {
         WebAssert.notNull("webWindow", webWindow);
         if (windows_.add(webWindow)) {
             fireWindowOpened(new WebWindowEvent(webWindow, WebWindowEvent.OPEN, webWindow.getEnclosedPage(), null));
         }
         // register JobManager here but don't deregister in deregisterWebWindow as it can live longer
         jobManagers_.add(new WeakReference<>(webWindow.getJobManager()));
     }
 
     /**
      * <span style="color:red">INTERNAL API - SUBJECT TO CHANGE AT ANY TIME - USE AT YOUR OWN RISK.</span><br>
      *
      * Removes a window from the list of available windows.
      *
      * @param webWindow the window to remove
      */
     public void deregisterWebWindow(final WebWindow webWindow) {
         WebAssert.notNull("webWindow", webWindow);
         if (windows_.remove(webWindow)) {
             fireWindowClosed(new WebWindowEvent(webWindow, WebWindowEvent.CLOSE, webWindow.getEnclosedPage(), null));
         }
     }
 
     /**
      * Expands a relative URL relative to the specified base. In most situations
      * this is the same as <code>new URL(baseUrl, relativeUrl)</code> but
      * there are some cases that URL doesn't handle correctly. See
      * <a href="http://www.faqs.org/rfcs/rfc1808.html">RFC1808</a>
      * regarding Relative Uniform Resource Locators for more information.
      *
      * @param baseUrl the base URL
      * @param relativeUrl the relative URL
      * @return the expansion of the specified base and relative URLs
      * @throws MalformedURLException if an error occurred when creating a URL object
      */
     public static URL expandUrl(final URL baseUrl, final String relativeUrl) throws MalformedURLException {
         final String newUrl = UrlUtils.resolveUrl(baseUrl, relativeUrl);
         return UrlUtils.toUrlUnsafe(newUrl);
     }
 
     private WebResponse makeWebResponseForDataUrl(final WebRequest webRequest) throws IOException {
         final URL url = webRequest.getUrl();
 
         final DataURLConnection connection = new DataURLConnection(url);
 
         final List<NameValuePair> responseHeaders = new ArrayList<>();
         responseHeaders.add(new NameValuePair(HttpHeader.CONTENT_TYPE_LC,
             connection.getMediaType() + ";charset=" + connection.getCharset()));
 
         if (HttpMethod.HEAD.equals(webRequest.getHttpMethod())) {
             final WebResponseData data = new WebResponseData(200, "OK", responseHeaders);
             return new WebResponse(data, url, webRequest.getHttpMethod(), 0);
         }
 
         try (InputStream is = connection.getInputStream()) {
             final DownloadedContent downloadedContent =
                     HttpWebConnection.downloadContent(is,
                             getOptions().getMaxInMemory(),
                             getOptions().getTempFileDirectory());
             final WebResponseData data = new WebResponseData(downloadedContent, 200, "OK", responseHeaders);
             return new WebResponse(data, url, webRequest.getHttpMethod(), 0);
         }
     }
 
     private static WebResponse makeWebResponseForAboutUrl(final WebRequest webRequest) throws MalformedURLException {
         final URL url = webRequest.getUrl();
         final String urlString = url.toExternalForm();
         if (UrlUtils.ABOUT_BLANK.equalsIgnoreCase(urlString)) {
             return new StringWebResponse("", UrlUtils.URL_ABOUT_BLANK);
         }
 
         final String urlWithoutQuery = StringUtils.substringBefore(urlString, "?");
         if (!"blank".equalsIgnoreCase(StringUtils.substringAfter(urlWithoutQuery, UrlUtils.ABOUT_SCHEME))) {
             throw new MalformedURLException(url + " is not supported, only about:blank is supported at the moment.");
         }
         return new StringWebResponse("", url);
     }
 
     /**
      * Builds a WebResponse for a file URL.
      * This first implementation is basic.
      * It assumes that the file contains an HTML page encoded with the specified encoding.
      * @param webRequest the request
      * @return the web response
      * @throws IOException if an IO problem occurs
      */
     private WebResponse makeWebResponseForFileUrl(final WebRequest webRequest) throws IOException {
         URL cleanUrl = webRequest.getUrl();
         if (cleanUrl.getQuery() != null) {
             // Get rid of the query portion before trying to load the file.
             cleanUrl = UrlUtils.getUrlWithNewQuery(cleanUrl, null);
         }
         if (cleanUrl.getRef() != null) {
             // Get rid of the ref portion before trying to load the file.
             cleanUrl = UrlUtils.getUrlWithNewRef(cleanUrl, null);
         }
 
         final WebResponse fromCache = getCache().getCachedResponse(webRequest);
         if (fromCache != null) {
             return new WebResponseFromCache(fromCache, webRequest);
         }
 
         String fileUrl = cleanUrl.toExternalForm();
         fileUrl = URLDecoder.decode(fileUrl, UTF_8.name());
         final File file = new File(fileUrl.substring(5));
         if (!file.exists()) {
             // construct 404
             final List<NameValuePair> compiledHeaders = new ArrayList<>();
             compiledHeaders.add(new NameValuePair(HttpHeader.CONTENT_TYPE, MimeType.TEXT_HTML));
             final WebResponseData responseData =
                 new WebResponseData(
                         StringUtils
                             .toByteArray("File: " + file.getAbsolutePath(), UTF_8),
                     404, "Not Found", compiledHeaders);
             return new WebResponse(responseData, webRequest, 0);
         }
 
         final String contentType = guessContentType(file);
 
         final DownloadedContent content = new DownloadedContent.OnFile(file, false);
         final List<NameValuePair> compiledHeaders = new ArrayList<>();
         compiledHeaders.add(new NameValuePair(HttpHeader.CONTENT_TYPE, contentType));
         compiledHeaders.add(new NameValuePair(HttpHeader.LAST_MODIFIED,
                 HttpUtils.formatDate(new Date(file.lastModified()))));
         final WebResponseData responseData = new WebResponseData(content, 200, "OK", compiledHeaders);
         final WebResponse webResponse = new WebResponse(responseData, webRequest, 0);
         getCache().cacheIfPossible(webRequest, webResponse, null);
         return webResponse;
     }
 
     private WebResponse makeWebResponseForBlobUrl(final WebRequest webRequest) {
         final Window window = getCurrentWindow().getScriptableObject();
         final Blob fileOrBlob = window.getDocument().resolveBlobUrl(webRequest.getUrl().toString());
         if (fileOrBlob == null) {
             throw JavaScriptEngine.typeError("Cannot load data from " + webRequest.getUrl());
         }
 
         final List<NameValuePair> headers = new ArrayList<>();
         final String type = fileOrBlob.getType();
         if (!StringUtils.isEmptyOrNull(type)) {
             headers.add(new NameValuePair(HttpHeader.CONTENT_TYPE, fileOrBlob.getType()));
         }
         if (fileOrBlob instanceof org.htmlunit.javascript.host.file.File) {
             final org.htmlunit.javascript.host.file.File file = (org.htmlunit.javascript.host.file.File) fileOrBlob;
             final String fileName = file.getName();
             if (!StringUtils.isEmptyOrNull(fileName)) {
                 // https://datatracker.ietf.org/doc/html/rfc6266#autoid-10
                 headers.add(new NameValuePair(HttpHeader.CONTENT_DISPOSITION, "inline; filename=\"" + fileName + "\""));
             }
         }
 
         final DownloadedContent content = new DownloadedContent.InMemory(fileOrBlob.getBytes());
         final WebResponseData responseData = new WebResponseData(content, 200, "OK", headers);
         return new WebResponse(responseData, webRequest, 0);
     }
 
     /**
      * Tries to guess the content type of the file.<br>
      * This utility could be located in a helper class but we can compare this functionality
      * for instance with the "Helper Applications" settings of Mozilla and therefore see it as a
      * property of the "browser".
      * @param file the file
      * @return "application/octet-stream" if nothing could be guessed
      */
     public String guessContentType(final File file) {
         final String fileName = file.getName();
         final String fileNameLC = fileName.toLowerCase(Locale.ROOT);
         if (fileNameLC.endsWith(".xhtml")) {
             // Java's mime type map returns application/xml in JDK8.
             return MimeType.APPLICATION_XHTML;
         }
 
         // Java's mime type map does not know these in JDK8.
         if (fileNameLC.endsWith(".js")) {
             return MimeType.TEXT_JAVASCRIPT;
         }
 
         if (fileNameLC.endsWith(".css")) {
             return MimeType.TEXT_CSS;
         }
 
         String contentType = null;
         if (!fileNameLC.endsWith(".php")) {
             contentType = URLConnection.guessContentTypeFromName(fileName);
         }
         if (contentType == null) {
             try (InputStream inputStream = new BufferedInputStream(Files.newInputStream(file.toPath()))) {
                 contentType = URLConnection.guessContentTypeFromStream(inputStream);
             }
             catch (final IOException ignored) {
                 // Ignore silently.
             }
         }
         if (contentType == null) {
             contentType = MimeType.APPLICATION_OCTET_STREAM;
         }
         return contentType;
     }
 
     private WebResponse makeWebResponseForJavaScriptUrl(final WebWindow webWindow, final URL url,
         final Charset charset) throws FailingHttpStatusCodeException, IOException {
 
         HtmlPage page = null;
         if (webWindow instanceof FrameWindow) {
             final FrameWindow frameWindow = (FrameWindow) webWindow;
             page = (HtmlPage) frameWindow.getEnclosedPage();
         }
         else {
             final Page currentPage = webWindow.getEnclosedPage();
             if (currentPage instanceof HtmlPage) {
                 page = (HtmlPage) currentPage;
             }
         }
 
         if (page == null) {
             page = getPage(webWindow, WebRequest.newAboutBlankRequest());
         }
         final ScriptResult r = page.executeJavaScript(url.toExternalForm(), "JavaScript URL", 1);
         if (r.getJavaScriptResult() == null || ScriptResult.isUndefined(r)) {
             // No new WebResponse to produce.
             return webWindow.getEnclosedPage().getWebResponse();
         }
 
         final String contentString = r.getJavaScriptResult().toString();
         final StringWebResponse response = new StringWebResponse(contentString, charset, url);
         response.setFromJavascript(true);
         return response;
     }
 
     /**
      * Loads a {@link WebResponse} from the server.
      * @param webRequest the request
      * @throws IOException if an IO problem occurs
      * @return the WebResponse
      */
     public WebResponse loadWebResponse(final WebRequest webRequest) throws IOException {
         final String protocol = webRequest.getUrl().getProtocol();
         switch (protocol) {
             case UrlUtils.ABOUT:
                 return makeWebResponseForAboutUrl(webRequest);
 
             case "file":
                 return makeWebResponseForFileUrl(webRequest);
 
             case "data":
                 return makeWebResponseForDataUrl(webRequest);
 
             case "blob":
                 return makeWebResponseForBlobUrl(webRequest);
 
             case "http":
             case "https":
                 return loadWebResponseFromWebConnection(webRequest, ALLOWED_REDIRECTIONS_SAME_URL);
 
             default:
                 throw new IOException("Unsupported protocol '" + protocol + "'");
         }
     }
 
     /**
      * Loads a {@link WebResponse} from the server through the WebConnection.
      * @param webRequest the request
      * @param allowedRedirects the number of allowed redirects remaining
      * @throws IOException if an IO problem occurs
      * @return the resultant {@link WebResponse}
      */
     private WebResponse loadWebResponseFromWebConnection(final WebRequest webRequest,
         final int allowedRedirects) throws IOException {
 
         URL url = webRequest.getUrl();
         final HttpMethod method = webRequest.getHttpMethod();
         final List<NameValuePair> parameters = webRequest.getRequestParameters();
 
         WebAssert.notNull("url", url);
         WebAssert.notNull("method", method);
         WebAssert.notNull("parameters", parameters);
 
         url = UrlUtils.encodeUrl(url, webRequest.getCharset());
         webRequest.setUrl(url);
 
         if (LOG.isDebugEnabled()) {
             LOG.debug("Load response for " + method + " " + url.toExternalForm());
         }
 
         // If the request settings don't specify a custom proxy, use the default client proxy...
         if (webRequest.getProxyHost() == null) {
             final ProxyConfig proxyConfig = getOptions().getProxyConfig();
             if (proxyConfig.getProxyAutoConfigUrl() != null) {
                 if (!UrlUtils.sameFile(new URL(proxyConfig.getProxyAutoConfigUrl()), url)) {
                     String content = proxyConfig.getProxyAutoConfigContent();
                     if (content == null) {
                         content = getPage(proxyConfig.getProxyAutoConfigUrl())
                             .getWebResponse().getContentAsString();
                         proxyConfig.setProxyAutoConfigContent(content);
                     }
                     final String allValue = JavaScriptEngine.evaluateProxyAutoConfig(getBrowserVersion(), content, url);
                     if (LOG.isDebugEnabled()) {
                         LOG.debug("Proxy Auto-Config: value '" + allValue + "' for URL " + url);
                     }
                     String value = allValue.split(";")[0].trim();
                     if (value.startsWith("PROXY")) {
                         value = value.substring(6);
                         final int colonIndex = value.indexOf(':');
                         webRequest.setSocksProxy(false);
                         webRequest.setProxyHost(value.substring(0, colonIndex));
                         webRequest.setProxyPort(Integer.parseInt(value.substring(colonIndex + 1)));
                     }
                     else if (value.startsWith("SOCKS")) {
                         value = value.substring(6);
                         final int colonIndex = value.indexOf(':');
                         webRequest.setSocksProxy(true);
                         webRequest.setProxyHost(value.substring(0, colonIndex));
                         webRequest.setProxyPort(Integer.parseInt(value.substring(colonIndex + 1)));
                     }
                 }
             }
             // ...unless the host needs to bypass the configured client proxy!
             else if (!proxyConfig.shouldBypassProxy(webRequest.getUrl().getHost())) {
                 webRequest.setProxyHost(proxyConfig.getProxyHost());
                 webRequest.setProxyPort(proxyConfig.getProxyPort());
                 webRequest.setProxyScheme(proxyConfig.getProxyScheme());
                 webRequest.setSocksProxy(proxyConfig.isSocksProxy());
             }
         }
 
         // Add the headers that are sent with every request.
         addDefaultHeaders(webRequest);
 
         // Retrieve the response, either from the cache or from the server.
         final WebResponse fromCache = getCache().getCachedResponse(webRequest);
         final WebResponse webResponse = getWebResponseOrUseCached(webRequest, fromCache);
 
         // Continue according to the HTTP status code.
         final int status = webResponse.getStatusCode();
         if (status == HttpStatus.USE_PROXY_305) {
             getIncorrectnessListener().notify("Ignoring HTTP status code [305] 'Use Proxy'", this);
         }
         else if (status >= HttpStatus.MOVED_PERMANENTLY_301
             && status <= HttpStatus.PERMANENT_REDIRECT_308
             && status != HttpStatus.NOT_MODIFIED_304
             && getOptions().isRedirectEnabled()) {
 
             final URL newUrl;
             String locationString = null;
             try {
                 locationString = webResponse.getResponseHeaderValue("Location");
                 if (locationString == null) {
                     return webResponse;
                 }
                 locationString = new String(locationString.getBytes(ISO_8859_1), UTF_8);
                 newUrl = expandUrl(url, locationString);
             }
             catch (final MalformedURLException e) {
                 getIncorrectnessListener().notify("Got a redirect status code [" + status + " "
                     + webResponse.getStatusMessage()
                     + "] but the location is not a valid URL [" + locationString
                     + "]. Skipping redirection processing.", this);
                 return webResponse;
             }
 
             if (LOG.isDebugEnabled()) {
                 LOG.debug("Got a redirect status code [" + status + "] new location = [" + locationString + "]");
             }
 
             if (allowedRedirects == 0) {
                 throw new FailingHttpStatusCodeException("Too many redirects for "
                     + webResponse.getWebRequest().getUrl(), webResponse);
             }
 
             if (status == HttpStatus.MOVED_PERMANENTLY_301
                     || status == HttpStatus.FOUND_302
                     || status == HttpStatus.SEE_OTHER_303) {
                 final WebRequest wrs = new WebRequest(newUrl, HttpMethod.GET);
                 wrs.setCharset(webRequest.getCharset());
 
                 if (HttpMethod.HEAD == webRequest.getHttpMethod()) {
                     wrs.setHttpMethod(HttpMethod.HEAD);
                 }
                 for (final Map.Entry<String, String> entry : webRequest.getAdditionalHeaders().entrySet()) {
                     wrs.setAdditionalHeader(entry.getKey(), entry.getValue());
                 }
                 return loadWebResponseFromWebConnection(wrs, allowedRedirects - 1);
             }
             else if (status == HttpStatus.TEMPORARY_REDIRECT_307
                         || status == HttpStatus.PERMANENT_REDIRECT_308) {
                 // https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/307
                 // https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/308
                 // reuse method and body
                 final WebRequest wrs = new WebRequest(newUrl, webRequest.getHttpMethod());
                 wrs.setCharset(webRequest.getCharset());
                 if (webRequest.getRequestBody() != null) {
                     if (HttpMethod.POST == webRequest.getHttpMethod()
                             || HttpMethod.PUT == webRequest.getHttpMethod()
                             || HttpMethod.PATCH == webRequest.getHttpMethod()) {
                         wrs.setRequestBody(webRequest.getRequestBody());
                         wrs.setEncodingType(webRequest.getEncodingType());
                     }
                 }
                 else {
                     wrs.setRequestParameters(parameters);
                 }
 
                 for (final Map.Entry<String, String> entry : webRequest.getAdditionalHeaders().entrySet()) {
                     wrs.setAdditionalHeader(entry.getKey(), entry.getValue());
                 }
 
                 return loadWebResponseFromWebConnection(wrs, allowedRedirects - 1);
             }
         }
 
         if (fromCache == null) {
             getCache().cacheIfPossible(webRequest, webResponse, null);
         }
         return webResponse;
     }
 
     /**
      * Returns the cached response provided for the request if usable otherwise makes the
      * request and returns the response.
      * @param webRequest the request
      * @param cached a previous cached response for the request, or {@code null}
      */
     private WebResponse getWebResponseOrUseCached(
             final WebRequest webRequest, final WebResponse cached) throws IOException {
         if (cached == null) {
             return getWebConnection().getResponse(webRequest);
         }
 
         if (!HeaderUtils.containsNoCache(cached)) {
             return new WebResponseFromCache(cached, webRequest);
         }
 
         // implementation based on rfc9111 https://www.rfc-editor.org/rfc/rfc9111#name-validation
         if (HeaderUtils.containsETag(cached)) {
             webRequest.setAdditionalHeader(HttpHeader.IF_NONE_MATCH, cached.getResponseHeaderValue(HttpHeader.ETAG));
         }
         if (HeaderUtils.containsLastModified(cached)) {
             webRequest.setAdditionalHeader(HttpHeader.IF_MODIFIED_SINCE,
                     cached.getResponseHeaderValue(HttpHeader.LAST_MODIFIED));
         }
 
         final WebResponse webResponse = getWebConnection().getResponse(webRequest);
 
         if (webResponse.getStatusCode() >= HttpStatus.INTERNAL_SERVER_ERROR_500) {
             return new WebResponseFromCache(cached, webRequest);
         }
 
         if (webResponse.getStatusCode() == HttpStatus.NOT_MODIFIED_304) {
             final Map<String, NameValuePair> header2NameValuePair = new LinkedHashMap<>();
             for (final NameValuePair pair : cached.getResponseHeaders()) {
                 header2NameValuePair.put(pair.getName(), pair);
             }
             for (final NameValuePair pair : webResponse.getResponseHeaders()) {
                 if (preferHeaderFrom304Response(pair.getName())) {
                     header2NameValuePair.put(pair.getName(), pair);
                 }
             }
             // WebResponse headers is unmodifiableList so we cannot update it directly
             // instead, create a new WebResponseFromCache with updated headers
             // then use it to replace the old cached value
             final WebResponse updatedCached =
                     new WebResponseFromCache(cached, new ArrayList<>(header2NameValuePair.values()), webRequest);
             getCache().cacheIfPossible(webRequest, updatedCached, null);
             return updatedCached;
         }
 
         getCache().cacheIfPossible(webRequest, webResponse, null);
         return webResponse;
     }
 
     /**
      * Returns true if the value of the specified header in a 304 Not Modified response should be
      * adopted over any previously cached value.
      */
     private static boolean preferHeaderFrom304Response(final String name) {
         final String lcName = name.toLowerCase(Locale.ROOT);
         for (final String header : DISCARDING_304_RESPONSE_HEADER_NAMES) {
             if (lcName.equals(header)) {
                 return false;
             }
         }
         for (final String prefix : DISCARDING_304_HEADER_PREFIXES) {
             if (lcName.startsWith(prefix)) {
                 return false;
             }
         }
         return true;
     }
 
     /**
      * Adds the headers that are sent with every request to the specified {@link WebRequest} instance.
      * @param wrs the <code>WebRequestSettings</code> instance to modify
      */
     private void addDefaultHeaders(final WebRequest wrs) {
         // Add user-specified headers to the web request if not present there yet.
         requestHeaders_.forEach((name, value) -> {
             if (!wrs.isAdditionalHeader(name)) {
                 wrs.setAdditionalHeader(name, value);
             }
         });
 
         // Add standard HtmlUnit headers to the web request if still not present there yet.
         if (!wrs.isAdditionalHeader(HttpHeader.ACCEPT_LANGUAGE)) {
             wrs.setAdditionalHeader(HttpHeader.ACCEPT_LANGUAGE, getBrowserVersion().getAcceptLanguageHeader());
         }
 
         if (!wrs.isAdditionalHeader(HttpHeader.SEC_FETCH_DEST)) {
             wrs.setAdditionalHeader(HttpHeader.SEC_FETCH_DEST, "document");
         }
         if (!wrs.isAdditionalHeader(HttpHeader.SEC_FETCH_MODE)) {
             wrs.setAdditionalHeader(HttpHeader.SEC_FETCH_MODE, "navigate");
         }
         if (!wrs.isAdditionalHeader(HttpHeader.SEC_FETCH_SITE)) {
             wrs.setAdditionalHeader(HttpHeader.SEC_FETCH_SITE, "same-origin");
         }
         if (!wrs.isAdditionalHeader(HttpHeader.SEC_FETCH_USER)) {
             wrs.setAdditionalHeader(HttpHeader.SEC_FETCH_USER, "?1");
         }
         if (getBrowserVersion().hasFeature(HTTP_HEADER_PRIORITY)
                 && !wrs.isAdditionalHeader(HttpHeader.PRIORITY)) {
             wrs.setAdditionalHeader(HttpHeader.PRIORITY, "u=0, i");
         }
 
         if (getBrowserVersion().hasFeature(HTTP_HEADER_CH_UA)
                 && !wrs.isAdditionalHeader(HttpHeader.SEC_CH_UA)) {
             wrs.setAdditionalHeader(HttpHeader.SEC_CH_UA, getBrowserVersion().getSecClientHintUserAgentHeader());
         }
         if (getBrowserVersion().hasFeature(HTTP_HEADER_CH_UA)
                 && !wrs.isAdditionalHeader(HttpHeader.SEC_CH_UA_MOBILE)) {
             wrs.setAdditionalHeader(HttpHeader.SEC_CH_UA_MOBILE, "?0");
         }
         if (getBrowserVersion().hasFeature(HTTP_HEADER_CH_UA)
                 && !wrs.isAdditionalHeader(HttpHeader.SEC_CH_UA_PLATFORM)) {
             wrs.setAdditionalHeader(HttpHeader.SEC_CH_UA_PLATFORM,
                     getBrowserVersion().getSecClientHintUserAgentPlatformHeader());
         }
 
         if (!wrs.isAdditionalHeader(HttpHeader.UPGRADE_INSECURE_REQUESTS)) {
             wrs.setAdditionalHeader(HttpHeader.UPGRADE_INSECURE_REQUESTS, "1");
         }
     }
 
     /**
      * Returns an immutable list of open web windows (whether they are top level windows or not).
      * This is a snapshot; future changes are not reflected by this list.
      * <p>
      * The list is ordered by age, the oldest one first.
      *
      * @return an immutable list of open web windows (whether they are top level windows or not)
      * @see #getWebWindowByName(String)
      * @see #getTopLevelWindows()
      */
     public List<WebWindow> getWebWindows() {
         return Collections.unmodifiableList(new ArrayList<>(windows_));
     }
 
     /**
      * <span style="color:red">INTERNAL API - SUBJECT TO CHANGE AT ANY TIME - USE AT YOUR OWN RISK.</span><br>
      *
      * Returns true if the list of WebWindows contains the provided one.
      * This method is there to improve the performance of some internal checks because
      * calling getWebWindows().contains(.) creates some objects without any need.
      *
      * @param webWindow the window to check
      * @return true or false
      */
     public boolean containsWebWindow(final WebWindow webWindow) {
         return windows_.contains(webWindow);
     }
 
     /**
      * Returns an immutable list of open top level windows.
      * This is a snapshot; future changes are not reflected by this list.
      * <p>
      * The list is ordered by age, the oldest one first.
      *
      * @return an immutable list of open top level windows
      * @see #getWebWindowByName(String)
      * @see #getWebWindows()
      */
     public List<TopLevelWindow> getTopLevelWindows() {
         return Collections.unmodifiableList(new ArrayList<>(topLevelWindows_));
     }
 
     /**
      * Sets the handler to be used whenever a refresh is triggered. Refer
      * to the documentation for {@link RefreshHandler} for more details.
      * @param handler the new handler
      */
     public void setRefreshHandler(final RefreshHandler handler) {
         if (handler == null) {
             refreshHandler_ = new NiceRefreshHandler(2);
         }
         else {
             refreshHandler_ = handler;
         }
     }
 
     /**
      * Returns the current refresh handler.
      * The default refresh handler is a {@link NiceRefreshHandler NiceRefreshHandler(2)}.
      * @return the current RefreshHandler
      */
     public RefreshHandler getRefreshHandler() {
         return refreshHandler_;
     }
 
     /**
      * Sets the script pre processor for this {@link WebClient}.
      * @param scriptPreProcessor the new preprocessor or null if none is specified
      */
     public void setScriptPreProcessor(final ScriptPreProcessor scriptPreProcessor) {
         scriptPreProcessor_ = scriptPreProcessor;
     }
 
     /**
      * Returns the script pre processor for this {@link WebClient}.
      * @return the pre processor or null of one hasn't been set
      */
     public ScriptPreProcessor getScriptPreProcessor() {
         return scriptPreProcessor_;
     }
 
     /**
      * Sets the listener for messages generated by the HTML parser.
      * @param listener the new listener, {@code null} if messages should be totally ignored
      */
     public void setHTMLParserListener(final HTMLParserListener listener) {
         htmlParserListener_ = listener;
     }
 
     /**
      * Gets the configured listener for messages generated by the HTML parser.
      * @return {@code null} if no listener is defined (default value)
      */
     public HTMLParserListener getHTMLParserListener() {
         return htmlParserListener_;
     }
 
     /**
      * Returns the CSS error handler used by this web client when CSS problems are encountered.
      * @return the CSS error handler used by this web client when CSS problems are encountered
      * @see DefaultCssErrorHandler
      * @see SilentCssErrorHandler
      */
     public CSSErrorHandler getCssErrorHandler() {
         return cssErrorHandler_;
     }
 
     /**
      * Sets the CSS error handler used by this web client when CSS problems are encountered.
      * @param cssErrorHandler the CSS error handler used by this web client when CSS problems are encountered
      * @see DefaultCssErrorHandler
      * @see SilentCssErrorHandler
      */
     public void setCssErrorHandler(final CSSErrorHandler cssErrorHandler) {
         WebAssert.notNull("cssErrorHandler", cssErrorHandler);
         cssErrorHandler_ = cssErrorHandler;
     }
 
     /**
      * Sets the number of milliseconds that a script is allowed to execute before being terminated.
      * A value of 0 or less means no timeout.
      *
      * @param timeout the timeout value, in milliseconds
      */
     public void setJavaScriptTimeout(final long timeout) {
         scriptEngine_.setJavaScriptTimeout(timeout);
     }
 
     /**
      * Returns the number of milliseconds that a script is allowed to execute before being terminated.
      * A value of 0 or less means no timeout.
      *
      * @return the timeout value, in milliseconds
      */
     public long getJavaScriptTimeout() {
         return scriptEngine_.getJavaScriptTimeout();
     }
 
     /**
      * Gets the current listener for encountered incorrectness (except HTML parsing messages that
      * are handled by the HTML parser listener). Default value is an instance of
      * {@link IncorrectnessListenerImpl}.
      * @return the current listener (not {@code null})
      */
     public IncorrectnessListener getIncorrectnessListener() {
         return incorrectnessListener_;
     }
 
     /**
      * Returns the current HTML incorrectness listener.
      * @param listener the new value (not {@code null})
      */
     public void setIncorrectnessListener(final IncorrectnessListener listener) {
         if (listener == null) {
             throw new IllegalArgumentException("Null is not a valid IncorrectnessListener");
         }
         incorrectnessListener_ = listener;
     }
 
     /**
      * Returns the WebConsole.
      * @return the web console
      */
     public WebConsole getWebConsole() {
         if (webConsole_ == null) {
             webConsole_ = new WebConsole();
         }
         return webConsole_;
     }
 
     /**
      * Gets the current AJAX controller.
      * @return the controller
      */
     public AjaxController getAjaxController() {
         return ajaxController_;
     }
 
     /**
      * Sets the current AJAX controller.
      * @param newValue the controller
      */
     public void setAjaxController(final AjaxController newValue) {
         if (newValue == null) {
             throw new IllegalArgumentException("Null is not a valid AjaxController");
         }
         ajaxController_ = newValue;
     }
 
     /**
      * Sets the attachment handler.
      * @param handler the new attachment handler
      */
     public void setAttachmentHandler(final AttachmentHandler handler) {
         attachmentHandler_ = handler;
     }
 
     /**
      * Returns the current attachment handler.
      * @return the current attachment handler
      */
     public AttachmentHandler getAttachmentHandler() {
         return attachmentHandler_;
     }
 
     /**
      * Sets the WebStart handler.
      * @param handler the new WebStart handler
      */
     public void setWebStartHandler(final WebStartHandler handler) {
         webStartHandler_ = handler;
     }
 
     /**
      * Returns the current WebStart handler.
      * @return the current WebStart handler
      */
     public WebStartHandler getWebStartHandler() {
         return webStartHandler_;
     }
 
     /**
      * Returns the current clipboard handler.
      * @return the current clipboard handler
      */
     public ClipboardHandler getClipboardHandler() {
         return clipboardHandler_;
     }
 
     /**
      * Sets the clipboard handler.
      * @param handler the new clipboard handler
      */
     public void setClipboardHandler(final ClipboardHandler handler) {
         clipboardHandler_ = handler;
     }
 
     /**
      * Returns the current {@link PrintHandler}.
      * @return the current {@link PrintHandler} or null if print
      *         requests are ignored
      */
     public PrintHandler getPrintHandler() {
         return printHandler_;
     }
 
     /**
      * Sets the {@link PrintHandler} to be used if Windoe.print() is called
      * (<a href="https://html.spec.whatwg.org/multipage/timers-and-user-prompts.html#printing">Printing Spec</a>).
      *
      * @param handler the new {@link PrintHandler} or null if you like to
      *        ignore print requests (default is null)
      */
     public void setPrintHandler(final PrintHandler handler) {
         printHandler_ = handler;
     }
 
     /**
      * Returns the current FrameContent handler.
      * @return the current FrameContent handler
      */
     public FrameContentHandler getFrameContentHandler() {
         return frameContentHandler_;
     }
 
     /**
      * Sets the FrameContent handler.
      * @param handler the new FrameContent handler
      */
     public void setFrameContentHandler(final FrameContentHandler handler) {
         frameContentHandler_ = handler;
     }
 
     /**
      * Sets the onbeforeunload handler for this {@link WebClient}.
      * @param onbeforeunloadHandler the new onbeforeunloadHandler or null if none is specified
      */
     public void setOnbeforeunloadHandler(final OnbeforeunloadHandler onbeforeunloadHandler) {
         onbeforeunloadHandler_ = onbeforeunloadHandler;
     }
 
     /**
      * Returns the onbeforeunload handler for this {@link WebClient}.
      * @return the onbeforeunload handler or null if one hasn't been set
      */
     public OnbeforeunloadHandler getOnbeforeunloadHandler() {
         return onbeforeunloadHandler_;
     }
 
     /**
      * Gets the cache currently being used.
      * @return the cache (may not be null)
      */
     public Cache getCache() {
         return cache_;
     }
 
     /**
      * Sets the cache to use.
      * @param cache the new cache (must not be {@code null})
      */
     public void setCache(final Cache cache) {
         if (cache == null) {
             throw new IllegalArgumentException("cache should not be null!");
         }
         cache_ = cache;
     }
 
     /**
      * Keeps track of the current window. Inspired by WebTest's logic to track the current response.
      */
     private static final class CurrentWindowTracker implements WebWindowListener, Serializable {
         private final WebClient webClient_;
         private final boolean ensureOneTopLevelWindow_;
 
         CurrentWindowTracker(final WebClient webClient, final boolean ensureOneTopLevelWindow) {
             webClient_ = webClient;
             ensureOneTopLevelWindow_ = ensureOneTopLevelWindow;
         }
 
         /**
          * {@inheritDoc}
          */
         @Override
         public void webWindowClosed(final WebWindowEvent event) {
             final WebWindow window = event.getWebWindow();
             if (window instanceof TopLevelWindow) {
                 webClient_.topLevelWindows_.remove(window);
                 if (window == webClient_.getCurrentWindow()) {
                     if (!webClient_.topLevelWindows_.isEmpty()) {
                         // The current window is now the previous top-level window.
                         webClient_.setCurrentWindow(
                                 webClient_.topLevelWindows_.get(webClient_.topLevelWindows_.size() - 1));
                     }
                 }
             }
             else if (window == webClient_.getCurrentWindow()) {
                 // The current window is now the last top-level window.
                 if (webClient_.topLevelWindows_.isEmpty()) {
                     webClient_.setCurrentWindow(null);
                 }
                 else {
                     webClient_.setCurrentWindow(
                             webClient_.topLevelWindows_.get(webClient_.topLevelWindows_.size() - 1));
                 }
             }
         }
 
         /**
          * Postprocessing to make sure we have always one top level window open.
          */
         public void afterWebWindowClosedListenersProcessed(final WebWindowEvent event) {
             if (!ensureOneTopLevelWindow_) {
                 return;
             }
 
             if (webClient_.topLevelWindows_.isEmpty()) {
                 // Must always have at least window, and there are no top-level windows left; must create one.
                 final TopLevelWindow newWindow = new TopLevelWindow("", webClient_);
                 webClient_.setCurrentWindow(newWindow);
             }
         }
 
         /**
          * {@inheritDoc}
          */
         @Override
         public void webWindowContentChanged(final WebWindowEvent event) {
             final WebWindow window = event.getWebWindow();
             boolean use = false;
             if (window instanceof DialogWindow) {
                 use = true;
             }
             else if (window instanceof TopLevelWindow) {
                 use = event.getOldPage() == null;
             }
             else if (window instanceof FrameWindow) {
                 final FrameWindow fw = (FrameWindow) window;
                 final String enclosingPageState = fw.getEnclosingPage().getDocumentElement().getReadyState();
                 final URL frameUrl = fw.getEnclosedPage().getUrl();
                 if (!DomNode.READY_STATE_COMPLETE.equals(enclosingPageState) || frameUrl == UrlUtils.URL_ABOUT_BLANK) {
                     return;
                 }
 
                 // now looks at the visibility of the frame window
                 final BaseFrameElement frameElement = fw.getFrameElement();
                 if (webClient_.isJavaScriptEnabled() && frameElement.isDisplayed()) {
                     final ComputedCssStyleDeclaration style = fw.getComputedStyle(frameElement, null);
                     use = style.getCalculatedWidth(false, false) != 0
                             && style.getCalculatedHeight(false, false) != 0;
                 }
             }
             if (use) {
                 webClient_.setCurrentWindow(window);
             }
         }
 
         /**
          * {@inheritDoc}
          */
         @Override
         public void webWindowOpened(final WebWindowEvent event) {
             final WebWindow window = event.getWebWindow();
             if (window instanceof TopLevelWindow) {
                 final TopLevelWindow tlw = (TopLevelWindow) window;
                 webClient_.topLevelWindows_.add(tlw);
             }
             // Page is not loaded yet, don't set it now as current window.
         }
     }
 
     /**
      * Closes all opened windows, stopping all background JavaScript processing.
      * The WebClient is not really usable after this - you have to create a new one or
      * use WebClient.reset() instead.
      * <p>
      * {@inheritDoc}
      */
     @Override
     public void close() {
         // avoid attaching new windows to the js engine
         if (scriptEngine_ != null) {
             scriptEngine_.prepareShutdown();
         }
 
         // stop the CurrentWindowTracker from making sure there is still one window available
         currentWindowTracker_ = new CurrentWindowTracker(this, false);
 
         // Hint: a new TopLevelWindow may be opened by some JS script while we are closing the others
         // but the prepareShutdown() call will prevent the new window form getting js support
         List<WebWindow> windows = new ArrayList<>(windows_);
         for (final WebWindow window : windows) {
             if (window instanceof TopLevelWindow) {
                 final TopLevelWindow topLevelWindow = (TopLevelWindow) window;
 
                 try {
                     topLevelWindow.close(true);
                 }
                 catch (final Exception e) {
                     LOG.error("Exception while closing a TopLevelWindow", e);
                 }
             }
             else if (window instanceof DialogWindow) {
                 final DialogWindow dialogWindow = (DialogWindow) window;
 
                 try {
                     dialogWindow.close();
                 }
                 catch (final Exception e) {
                     LOG.error("Exception while closing a DialogWindow", e);
                 }
             }
         }
 
         // second round, none of the remaining windows should be registered to
         // the js engine because of prepareShutdown()
         windows = new ArrayList<>(windows_);
         for (final WebWindow window : windows) {
             if (window instanceof TopLevelWindow) {
                 final TopLevelWindow topLevelWindow = (TopLevelWindow) window;
 
                 try {
                     topLevelWindow.close(true);
                 }
                 catch (final Exception e) {
                     LOG.error("Exception while closing a TopLevelWindow", e);
                 }
             }
             else if (window instanceof DialogWindow) {
                 final DialogWindow dialogWindow = (DialogWindow) window;
 
                 try {
                     dialogWindow.close();
                 }
                 catch (final Exception e) {
                     LOG.error("Exception while closing a DialogWindow", e);
                 }
             }
         }
 
         // now both lists have to be empty
         if (!topLevelWindows_.isEmpty()) {
             LOG.error("Sill " + topLevelWindows_.size() + " top level windows are open. Please report this error!");
             topLevelWindows_.clear();
         }
 
         if (!windows_.isEmpty()) {
             LOG.error("Sill " + windows_.size() + " windows are open. Please report this error!");
             windows_.clear();
         }
         currentWindow_ = null;
 
         ThreadDeath toThrow = null;
         if (scriptEngine_ != null) {
             try {
                 scriptEngine_.shutdown();
             }
             catch (final ThreadDeath ex) {
                 // make sure the following cleanup is performed to avoid resource leaks
                 toThrow = ex;
             }
             catch (final Exception e) {
                 LOG.error("Exception while shutdown the scriptEngine", e);
             }
         }
         scriptEngine_ = null;
 
         if (webConnection_ != null) {
             try {
                 webConnection_.close();
             }
             catch (final Exception e) {
                 LOG.error("Exception while closing the connection", e);
             }
         }
         webConnection_ = null;
 
         synchronized (this) {
             if (executor_ != null) {
                 try {
                     executor_.shutdownNow();
                 }
                 catch (final Exception e) {
                     LOG.error("Exception while shutdown the executor service", e);
                 }
             }
         }
         executor_ = null;
 
         cache_.clear();
         if (toThrow != null) {
             throw toThrow;
         }
     }
 
     /**
      * <p><span style="color:red">Experimental API: May be changed in next release
      * and may not yet work perfectly!</span></p>
      *
      * <p>This shuts down the whole client and restarts with a new empty window.
      * Cookies and other states are preserved.
      */
     public void reset() {
         close();
 
         // this has to be done after the browser version was set
         webConnection_ = new HttpWebConnection(this);
         if (javaScriptEngineEnabled_) {
             scriptEngine_ = new JavaScriptEngine(this);
         }
 
         // The window must be constructed AFTER the script engine.
         currentWindowTracker_ = new CurrentWindowTracker(this, true);
         currentWindow_ = new TopLevelWindow("", this);
     }
 
     /**
      * <p>Blocks until all background JavaScript tasks have finished executing or until the specified
      * timeout is reached, whichever occurs first. Background JavaScript tasks include:</p>
      * <ul>
      *   <li>JavaScript scheduled via <code>window.setTimeout()</code></li>
      *   <li>JavaScript scheduled via <code>window.setInterval()</code></li>
      *   <li>Asynchronous <code>XMLHttpRequest</code> operations</li>
      *   <li>Other asynchronous JavaScript operations across all windows managed by this WebClient</li>
      * </ul>
      *
      * <p><strong>Timeout Behavior:</strong> If background tasks are scheduled to execute after
      * <code>(now + timeoutMillis)</code>, this method will wait for the full timeout duration
      * and then return the number of remaining jobs. The method guarantees it will never block
      * longer than the specified timeout.</p>
      *
      * <p><strong>Use Case:</strong> Use this method when you don't know the exact timing of when
      * background JavaScript will start, but you have a reasonable estimate of how long all
      * tasks should take to complete. For scenarios where you know when tasks should start
      * executing, consider using {@link #waitForBackgroundJavaScriptStartingBefore(long)} instead.</p>
      *
      * <p><strong>Thread Safety:</strong> This method is thread-safe and handles concurrent
      * modifications to the internal job manager list gracefully.</p>
      *
      * <p><strong>Example Usage:</strong></p>
      * <pre><code>
      * // Wait up to 5 seconds for all background JavaScript to complete
      * int remainingJobs = webClient.waitForBackgroundJavaScript(5000);
      * if (remainingJobs == 0) {
      *     log("All background JavaScript completed");
      * } else {
      *     log("Timeout reached, " + remainingJobs + " jobs still pending");
      * }
      * </code></pre>
      *
      * @param timeoutMillis the maximum amount of time to wait in milliseconds; must be positive
      * @return the number of background JavaScript jobs still executing or waiting to be executed
      *         when this method returns; returns <code>0</code> if all jobs completed successfully
      *         within the timeout period
      * @throws IllegalArgumentException if timeoutMillis is negative
      * @see #waitForBackgroundJavaScriptStartingBefore(long)
      * @see #waitForBackgroundJavaScriptStartingBefore(long, long)
      */
     public int waitForBackgroundJavaScript(final long timeoutMillis) {
         int count = 0;
         final long endTime = System.currentTimeMillis() + timeoutMillis;
         for (Iterator<WeakReference<JavaScriptJobManager>> i = jobManagers_.iterator(); i.hasNext();) {
             final JavaScriptJobManager jobManager;
             final WeakReference<JavaScriptJobManager> reference;
             try {
                 reference = i.next();
                 jobManager = reference.get();
                 if (jobManager == null) {
                     i.remove();
                     continue;
                 }
             }
             catch (final ConcurrentModificationException e) {
                 i = jobManagers_.iterator();
                 count = 0;
                 continue;
             }
 
             final long newTimeout = endTime - System.currentTimeMillis();
             count += jobManager.waitForJobs(newTimeout);
         }
         if (count != getAggregateJobCount()) {
             final long newTimeout = endTime - System.currentTimeMillis();
             return waitForBackgroundJavaScript(newTimeout);
         }
         return count;
     }
 
     /**
      * <p>Blocks until all background JavaScript tasks scheduled to start executing before
      * <code>(now + delayMillis)</code> have finished executing. Background JavaScript tasks include:</p>
      * <ul>
      *   <li>JavaScript scheduled via <code>window.setTimeout()</code></li>
      *   <li>JavaScript scheduled via <code>window.setInterval()</code></li>
      *   <li>Asynchronous <code>XMLHttpRequest</code> operations</li>
      *   <li>Other asynchronous JavaScript operations across all windows managed by this WebClient</li>
      * </ul>
      *
      * <p><strong>Method Behavior:</strong></p>
      * <ul>
      *   <li>If no background JavaScript tasks are currently executing and none are scheduled
      *       to start within <code>delayMillis</code>, this method returns immediately</li>
      *   <li>Tasks scheduled to execute after <code>(now + delayMillis)</code> are ignored
      *       and do not affect the waiting behavior</li>
      *   <li>The method waits for tasks to complete execution, not just to start</li>
      *   <li>This method waits indefinitely for qualifying tasks to complete (no timeout)</li>
      * </ul>
      *
      * <p><strong>Use Case:</strong> This method is ideal when you know approximately when
      * background JavaScript should start executing but are uncertain about execution duration.
      * Use this when you don't need a timeout and want to ensure all relevant tasks complete.
      * For scenarios where you need to wait for all background tasks regardless of timing,
      * use {@link #waitForBackgroundJavaScript(long)} instead. For timeout control, use
      * {@link #waitForBackgroundJavaScriptStartingBefore(long, long)} instead.</p>
      *
      * <p><strong>Thread Safety:</strong> This method is thread-safe and handles concurrent
      * modifications to the internal job manager list gracefully.</p>
      *
      * <p><strong>Example Usage:</strong></p>
      * <pre><code>
      * // Wait indefinitely for JavaScript tasks starting within 1 second
      * int remainingJobs = webClient.waitForBackgroundJavaScriptStartingBefore(1000);
      * if (remainingJobs == 0) {
      *     log("All relevant background JavaScript completed");
      * } else {
      *     log("Some tasks may still be pending: " + remainingJobs + " jobs");
      * }
      *
      * // Common pattern: wait for tasks that should start soon
      * // (useful after triggering an action that schedules JavaScript)
      * webClient.waitForBackgroundJavaScriptStartingBefore(500);
      * </code></pre>
      *
      * @param delayMillis the delay which determines the background tasks to wait for (in milliseconds);
      *                   must be non-negative
      * @return the number of background JavaScript jobs still executing or waiting to be executed
      *         when this method returns; returns <code>0</code> if all qualifying jobs completed
      *         successfully
      * @see #waitForBackgroundJavaScript(long)
      * @see #waitForBackgroundJavaScriptStartingBefore(long, long)
      */
     public int waitForBackgroundJavaScriptStartingBefore(final long delayMillis) {
         return waitForBackgroundJavaScriptStartingBefore(delayMillis, -1);
     }
 
     /**
      * <p>Blocks until all background JavaScript tasks scheduled to start executing before
      * <code>(now + delayMillis)</code> have finished executing, or until the specified timeout
      * is reached, whichever occurs first. Background JavaScript tasks include:</p>
      * <ul>
      *   <li>JavaScript scheduled via <code>window.setTimeout()</code></li>
      *   <li>JavaScript scheduled via <code>window.setInterval()</code></li>
      *   <li>Asynchronous <code>XMLHttpRequest</code> operations</li>
      *   <li>Other asynchronous JavaScript operations across all windows managed by this WebClient</li>
      * </ul>
      *
      * <p><strong>Method Behavior:</strong></p>
      * <ul>
      *   <li>If no background JavaScript tasks are currently executing and none are scheduled
      *       to start within <code>delayMillis</code>, this method returns immediately</li>
      *   <li>Tasks scheduled to execute after <code>(now + delayMillis)</code> are ignored
      *       and do not affect the waiting behavior</li>
      *   <li>The method waits for tasks to complete execution, not just to start</li>
      * </ul>
      *
      * <p><strong>Timeout Behavior:</strong></p>
      * <ul>
      *   <li>If <code>timeoutMillis</code> is negative or less than <code>delayMillis</code>,
      *       the timeout is ignored and the method waits indefinitely</li>
      *   <li>When a valid timeout is specified, the method will never block longer than
      *       <code>timeoutMillis</code> milliseconds</li>
      *   <li>The timeout applies to the total waiting time, not per task</li>
      * </ul>
      *
      * <p><strong>Use Case:</strong> This method is ideal when you know approximately when
      * background JavaScript should start executing but are uncertain about execution duration.
      * For scenarios where you need to wait for all background tasks regardless of timing,
      * use {@link #waitForBackgroundJavaScript(long)} instead.</p>
      *
      * <p><strong>Thread Safety:</strong> This method is thread-safe and handles concurrent
      * modifications to the internal job manager list gracefully.</p>
      *
      * <p><strong>Example Usage:</strong></p>
      * <pre><code>
      * // Wait for JavaScript tasks starting within 1 second, with 10 second max timeout
      * int remainingJobs = webClient.waitForBackgroundJavaScriptStartingBefore(1000, 10000);
      * if (remainingJobs == 0) {
      *     log("All relevant background JavaScript completed");
      * } else {
      *     log("Timeout reached or tasks still pending: " + remainingJobs + " jobs");
      * }
      *
      * // Wait indefinitely for tasks starting within 500ms (timeout ignored)
      * webClient.waitForBackgroundJavaScriptStartingBefore(500, 100); // timeout &lt; delay
      * </code></pre>
      *
      * @param delayMillis the delay which determines the background tasks to wait for (in milliseconds);
      *                   must be non-negative
      * @param timeoutMillis the maximum amount of time to wait (in milliseconds); if negative or
      *                     less than <code>delayMillis</code>, the timeout is ignored and the method
      *                     waits indefinitely for qualifying tasks to complete
      * @return the number of background JavaScript jobs still executing or waiting to be executed
      *         when this method returns; returns <code>0</code> if all qualifying jobs completed
      *         successfully within the specified constraints
      * @see #waitForBackgroundJavaScript(long)
      * @see #waitForBackgroundJavaScriptStartingBefore(long)
      */
     public int waitForBackgroundJavaScriptStartingBefore(final long delayMillis, final long timeoutMillis) {
         int count = 0;
         long now = System.currentTimeMillis();
         final long endTime = now + delayMillis;
         long endTimeout = now + timeoutMillis;
         if (timeoutMillis < 0 || timeoutMillis < delayMillis) {
             endTimeout = -1;
         }
 
         for (Iterator<WeakReference<JavaScriptJobManager>> i = jobManagers_.iterator(); i.hasNext();) {
             final JavaScriptJobManager jobManager;
             final WeakReference<JavaScriptJobManager> reference;
             try {
                 reference = i.next();
                 jobManager = reference.get();
                 if (jobManager == null) {
                     i.remove();
                     continue;
                 }
             }
             catch (final ConcurrentModificationException e) {
                 i = jobManagers_.iterator();
                 count = 0;
                 continue;
             }
             now = System.currentTimeMillis();
             final long newDelay = endTime - now;
             final long newTimeout = (endTimeout == -1) ? -1 : endTimeout - now;
             count += jobManager.waitForJobsStartingBefore(newDelay, newTimeout);
         }
         if (count != getAggregateJobCount()) {
             now = System.currentTimeMillis();
             final long newDelay = endTime - now;
             final long newTimeout = (endTimeout == -1) ? -1 : endTimeout - now;
             return waitForBackgroundJavaScriptStartingBefore(newDelay, newTimeout);
         }
         return count;
     }
 
     /**
      * Returns the aggregate background JavaScript job count across all windows.
      * @return the aggregate background JavaScript job count across all windows
      */
     private int getAggregateJobCount() {
         int count = 0;
         for (Iterator<WeakReference<JavaScriptJobManager>> i = jobManagers_.iterator(); i.hasNext();) {
             final JavaScriptJobManager jobManager;
             final WeakReference<JavaScriptJobManager> reference;
             try {
                 reference = i.next();
                 jobManager = reference.get();
                 if (jobManager == null) {
                     i.remove();
                     continue;
                 }
             }
             catch (final ConcurrentModificationException e) {
                 i = jobManagers_.iterator();
                 count = 0;
                 continue;
             }
             final int jobCount = jobManager.getJobCount();
             count += jobCount;
         }
         return count;
     }
 
     /**
      * When we deserialize, re-initializie transient fields.
      * @param in the object input stream
      * @throws IOException if an error occurs
      * @throws ClassNotFoundException if an error occurs
      */
     private void readObject(final ObjectInputStream in) throws IOException, ClassNotFoundException {
         in.defaultReadObject();
 
         webConnection_ = new HttpWebConnection(this);
         scriptEngine_ = new JavaScriptEngine(this);
         jobManagers_ = Collections.synchronizedList(new ArrayList<>());
         loadQueue_ = new ArrayList<>();
         css3ParserPool_ = new CSS3ParserPool();
         broadcastChannel_ = new HashSet<>();
     }
 
     private static class LoadJob {
         private final WebWindow requestingWindow_;
         private final String target_;
         private final WebResponse response_;
         private final WeakReference<Page> originalPage_;
         private final WebRequest request_;
         private final String forceAttachmentWithFilename_;
 
         // we can't us the WebRequest from the WebResponse because
         // we need the original request e.g. after a redirect
         LoadJob(final WebRequest request, final WebResponse response,
                 final WebWindow requestingWindow, final String target, final String forceAttachmentWithFilename) {
             request_ = request;
             requestingWindow_ = requestingWindow;
             target_ = target;
             response_ = response;
             originalPage_ = new WeakReference<>(requestingWindow.getEnclosedPage());
             forceAttachmentWithFilename_ = forceAttachmentWithFilename;
         }
 
         public boolean isOutdated() {
             if (target_ != null && !target_.isEmpty()) {
                 return false;
             }
 
             if (requestingWindow_.isClosed()) {
                 return true;
             }
 
             if (requestingWindow_.getEnclosedPage() != originalPage_.get()) {
                 return true;
             }
 
             return false;
         }
     }
 
     /**
      * <span style="color:red">INTERNAL API - SUBJECT TO CHANGE AT ANY TIME - USE AT YOUR OWN RISK.</span><br>
      *
      * Perform the downloads and stores it for loading later into a window.
      * In the future downloads should be performed in parallel in separated threads.
      * TODO: refactor it before next release.
      * @param requestingWindow the window from which the request comes
      * @param target the name of the target window
      * @param request the request to perform
      * @param checkHash if true check for hashChenage
      * @param forceAttachmentWithFilename if not {@code null} the AttachmentHandler isAttachment() method is not called,
      *        the response has to be handled as attachment in any case
      * @param description information about the origin of the request. Useful for debugging.
      */
     public void download(final WebWindow requestingWindow, final String target,
         final WebRequest request, final boolean checkHash,
         final String forceAttachmentWithFilename, final String description) {
 
         final WebWindow targetWindow = resolveWindow(requestingWindow, target);
         final URL url = request.getUrl();
 
         if (targetWindow != null && HttpMethod.POST != request.getHttpMethod()) {
             final Page page = targetWindow.getEnclosedPage();
             if (page != null) {
                 if (page.isHtmlPage() && !((HtmlPage) page).isOnbeforeunloadAccepted()) {
                     return;
                 }
 
                 if (checkHash) {
                     final URL current = page.getUrl();
                     final boolean justHashJump =
                             HttpMethod.GET == request.getHttpMethod()
                             && UrlUtils.sameFile(url, current)
                             && null != url.getRef();
 
                     if (justHashJump) {
                         processOnlyHashChange(targetWindow, url);
                         return;
                     }
                 }
             }
         }
 
         synchronized (loadQueue_) {
             // verify if this load job doesn't already exist
             for (final LoadJob otherLoadJob : loadQueue_) {
                 if (otherLoadJob.response_ == null) {
                     continue;
                 }
                 final WebRequest otherRequest = otherLoadJob.request_;
                 final URL otherUrl = otherRequest.getUrl();
 
                 if (url.getPath().equals(otherUrl.getPath()) // fail fast
                     && url.toString().equals(otherUrl.toString())
                     && request.getRequestParameters().equals(otherRequest.getRequestParameters())
                     && Objects.equals(request.getRequestBody(), otherRequest.getRequestBody())) {
                     return; // skip it;
                 }
             }
         }
 
         final LoadJob loadJob;
         try {
             WebResponse response;
             try {
                 response = loadWebResponse(request);
             }
             catch (final NoHttpResponseException e) {
                 LOG.error("NoHttpResponseException while downloading; generating a NoHttpResponse", e);
                 response = new WebResponse(RESPONSE_DATA_NO_HTTP_RESPONSE, request, 0);
             }
             loadJob = new LoadJob(request, response, requestingWindow, target, forceAttachmentWithFilename);
         }
         catch (final IOException e) {
             throw new RuntimeException(e);
         }
 
         synchronized (loadQueue_) {
             loadQueue_.add(loadJob);
         }
     }
 
     /**
      * <span style="color:red">INTERNAL API - SUBJECT TO CHANGE AT ANY TIME - USE AT YOUR OWN RISK.</span><br>
      *
      * Loads downloaded responses into the corresponding windows.
      * TODO: refactor it before next release.
      * @throws IOException in case of exception
      * @throws FailingHttpStatusCodeException in case of exception
      */
     public void loadDownloadedResponses() throws FailingHttpStatusCodeException, IOException {
         final List<LoadJob> queue;
 
         // synchronize access to the loadQueue_,
         // to be sure no job is ignored
         synchronized (loadQueue_) {
             if (loadQueue_.isEmpty()) {
                 return;
             }
             queue = new ArrayList<>(loadQueue_);
             loadQueue_.clear();
         }
 
         final HashSet<WebWindow> updatedWindows = new HashSet<>();
         for (int i = queue.size() - 1; i >= 0; --i) {
             final LoadJob loadJob = queue.get(i);
             if (loadJob.isOutdated()) {
                 if (LOG.isInfoEnabled()) {
                     LOG.info("No usage of download: " + loadJob);
                 }
                 continue;
             }
 
             final WebWindow window = resolveWindow(loadJob.requestingWindow_, loadJob.target_);
             if (updatedWindows.contains(window)) {
                 if (LOG.isInfoEnabled()) {
                     LOG.info("No usage of download: " + loadJob);
                 }
                 continue;
             }
 
             final WebWindow win = openTargetWindow(loadJob.requestingWindow_, loadJob.target_, TARGET_SELF);
             final Page pageBeforeLoad = win.getEnclosedPage();
             loadWebResponseInto(loadJob.response_, win, loadJob.forceAttachmentWithFilename_);
 
             // start execution here.
             if (scriptEngine_ != null) {
                 scriptEngine_.registerWindowAndMaybeStartEventLoop(win);
             }
 
             if (pageBeforeLoad != win.getEnclosedPage()) {
                 updatedWindows.add(win);
             }
 
             // check and report problems if needed
             throwFailingHttpStatusCodeExceptionIfNecessary(loadJob.response_);
         }
     }
 
     private static void processOnlyHashChange(final WebWindow window, final URL urlWithOnlyHashChange) {
         final Page page = window.getEnclosedPage();
         final String oldURL = page.getUrl().toExternalForm();
 
         // update request url
         final WebRequest req = page.getWebResponse().getWebRequest();
         req.setUrl(urlWithOnlyHashChange);
 
         // update location.hash
         final Window jsWindow = window.getScriptableObject();
         if (null != jsWindow) {
             final Location location = jsWindow.getLocation();
             location.setHash(oldURL, urlWithOnlyHashChange.getRef());
         }
 
         // add to history
         window.getHistory().addPage(page);
     }
 
     /**
      * Returns the options object of this WebClient.
      * @return the options object
      */
     public WebClientOptions getOptions() {
         return options_;
     }
 
     /**
      * Gets the holder for the different storages.
      * <p><span style="color:red">Experimental API: May be changed in next release!</span></p>
      * @return the holder
      */
     public StorageHolder getStorageHolder() {
         return storageHolder_;
     }
 
     /**
      * Returns the currently configured cookies applicable to the specified URL, in an unmodifiable set.
      * If disabled, this returns an empty set.
      * @param url the URL on which to filter the returned cookies
      * @return the currently configured cookies applicable to the specified URL, in an unmodifiable set
      */
     public synchronized Set<Cookie> getCookies(final URL url) {
         final CookieManager cookieManager = getCookieManager();
 
         if (!cookieManager.isCookiesEnabled()) {
             return Collections.emptySet();
         }
 
         final URL normalizedUrl = HttpClientConverter.replaceForCookieIfNecessary(url);
 
         final String host = normalizedUrl.getHost();
         // URLs like "about:blank" don't have cookies and we need to catch these
         // cases here before HttpClient complains
         if (host.isEmpty()) {
             return Collections.emptySet();
         }
 
         // discard expired cookies
         cookieManager.clearExpired(new Date());
 
         final Set<Cookie> matchingCookies = new LinkedHashSet<>();
         HttpClientConverter.addMatching(cookieManager.getCookies(), normalizedUrl,
                 getBrowserVersion(), matchingCookies);
         return Collections.unmodifiableSet(matchingCookies);
     }
 
     /**
      * Parses the given cookie and adds this to our cookie store.
      * @param cookieString the string to parse
      * @param pageUrl the url of the page that likes to set the cookie
      * @param origin the requester
      */
     public void addCookie(final String cookieString, final URL pageUrl, final Object origin) {
         final CookieManager cookieManager = getCookieManager();
         if (!cookieManager.isCookiesEnabled()) {
             if (LOG.isDebugEnabled()) {
                 LOG.debug("Skipped adding cookie: '" + cookieString
                         + "' because cookies are not enabled for the CookieManager.");
             }
             return;
         }
 
         try {
             final List<Cookie> cookies = HttpClientConverter.parseCookie(cookieString, pageUrl, getBrowserVersion());
 
             for (final Cookie cookie : cookies) {
                 cookieManager.addCookie(cookie);
 
                 if (LOG.isDebugEnabled()) {
                     LOG.debug("Added cookie: '" + cookieString + "'");
                 }
             }
         }
         catch (final MalformedCookieException e) {
             if (LOG.isDebugEnabled()) {
                 LOG.warn("Adding cookie '" + cookieString + "' failed.", e);
             }
             getIncorrectnessListener().notify("Adding cookie '" + cookieString
                         + "' failed; reason: '" + e.getMessage() + "'.", origin);
         }
     }
 
     /**
      * Returns true if the javaScript support is enabled.
      * To disable the javascript support (eg. temporary)
      * you have to use the {@link WebClientOptions#setJavaScriptEnabled(boolean)} setter.
      * @see #isJavaScriptEngineEnabled()
      * @see WebClientOptions#isJavaScriptEnabled()
      * @return true if the javaScript engine and the javaScript support is enabled.
      */
     public boolean isJavaScriptEnabled() {
         return javaScriptEngineEnabled_ && getOptions().isJavaScriptEnabled();
     }
 
     /**
      * Returns true if the javaScript engine is enabled.
      * To disable the javascript engine you have to use the
      * {@link WebClient#WebClient(BrowserVersion, boolean, String, int)} constructor.
      * @return true if the javaScript engine is enabled.
      */
     public boolean isJavaScriptEngineEnabled() {
         return javaScriptEngineEnabled_;
     }
 
     /**
      * Parses the given XHtml code string and loads the resulting XHtmlPage into
      * the current window.
      *
      * @param htmlCode the html code as string
      * @return the HtmlPage
      * @throws IOException in case of error
      */
     public HtmlPage loadHtmlCodeIntoCurrentWindow(final String htmlCode) throws IOException {
         final HTMLParser htmlParser = getPageCreator().getHtmlParser();
         final WebWindow webWindow = getCurrentWindow();
 
         final StringWebResponse webResponse =
                 new StringWebResponse(htmlCode, new URL("https://www.htmlunit.org/dummy.html"));
         final HtmlPage page = new HtmlPage(webResponse, webWindow);
         webWindow.setEnclosedPage(page);
 
         htmlParser.parse(this, webResponse, page, false, false);
         return page;
     }
 
     /**
      * Parses the given XHtml code string and loads the resulting XHtmlPage into
      * the current window.
      *
      * @param xhtmlCode the xhtml code as string
      * @return the XHtmlPage
      * @throws IOException in case of error
      */
     public XHtmlPage loadXHtmlCodeIntoCurrentWindow(final String xhtmlCode) throws IOException {
         final HTMLParser htmlParser = getPageCreator().getHtmlParser();
         final WebWindow webWindow = getCurrentWindow();
 
         final StringWebResponse webResponse =
                 new StringWebResponse(xhtmlCode, new URL("https://www.htmlunit.org/dummy.html"));
         final XHtmlPage page = new XHtmlPage(webResponse, webWindow);
         webWindow.setEnclosedPage(page);
 
         htmlParser.parse(this, webResponse, page, true, false);
         return page;
     }
 
     /**
      * Creates a new {@link WebSocketAdapter}.
      *
      * @param webSocketListener the {@link WebSocketListener}
      * @return a new {@link WebSocketAdapter}
      */
     public WebSocketAdapter buildWebSocketAdapter(final WebSocketListener webSocketListener) {
         return webSocketAdapterFactory_.buildWebSocketAdapter(this, webSocketListener);
     }
 
     /**
      * Defines a new factory method to create a new WebSocketAdapter.
      *
      * @param factory a {@link WebSocketAdapterFactory}
      */
     public void setWebSocketAdapter(final WebSocketAdapterFactory factory) {
         webSocketAdapterFactory_ = factory;
     }
 
     /**
      * <span style="color:red">INTERNAL API - SUBJECT TO CHANGE AT ANY TIME - USE AT YOUR OWN RISK.</span><br>
      *
      * @return a CSS3Parser that will return to an internal pool for reuse if closed using the
      *         try-with-resource concept
      */
     public PooledCSS3Parser getCSS3Parser() {
         return this.css3ParserPool_.get();
     }
 
     /**
      * <span style="color:red">INTERNAL API - SUBJECT TO CHANGE AT ANY TIME - USE AT YOUR OWN RISK.</span><br>
      *
      * @return the set of known {@link BroadcastChannel}s
      */
     public Set<BroadcastChannel> getBroadcastChannels() {
         return broadcastChannel_;
     }
 
     /**
      * Our pool of CSS3Parsers. If you need a parser, get it from here and use the AutoCloseable
      * functionality with a try-with-resource block. If you don't want to do that at all, continue
      * to build CSS3Parsers the old fashioned way.
      * <p>
      * Fetching a parser is thread safe. This API is built to minimize synchronization overhead,
      * hence it is possible to miss a returned parser from another thread under heavy pressure,
      * but because that is unlikely, we keep it simple and efficient. Caches are not supposed
      * to give cutting-edge guarantees.
      * <p>
      * This concept avoids a resource leak when someone does not close the fetched
      * parser because the pool does not know anything about the parser unless
      * it returns. We are not running a checkout-checkin concept.
      * <p>
      * <span style="color:red">INTERNAL API - SUBJECT TO CHANGE AT ANY TIME - USE AT YOUR OWN RISK.</span><br>
      */
     static class CSS3ParserPool {
         /*
          * Our pool. We only hold data when it is available. In addition, synchronization against
          * this deque is cheap.
          */
         private final ConcurrentLinkedDeque<PooledCSS3Parser> parsers_ = new ConcurrentLinkedDeque<>();
 
         /**
          * Fetch a new or recycled CSS3parser. Make sure you use the try-with-resource concept
          * to automatically return it after use because a parser creation is expensive.
          * We won't get a leak, if you don't do so, but that will remove the advantage.
          *
          * @return a parser
          */
         public PooledCSS3Parser get() {
             // see if we have one, LIFO
             final PooledCSS3Parser parser = parsers_.pollLast();
 
             // if we don't have one, get us one
             return parser != null ? parser.markInUse(this) : new PooledCSS3Parser(this);
         }
 
         /**
          * Return a parser. Normally you don't have to use that method explicitly.
          * Prefer to user the AutoCloseable interface of the PooledParser by
          * using a try-with-resource statement.
          *
          * @param parser the parser to recycle
          */
         protected void recycle(final PooledCSS3Parser parser) {
             parsers_.addLast(parser);
         }
     }
 
     /**
      * This is a poolable CSS3Parser which can be reused automatically when closed.
      * A regular CSS3Parser is not thread-safe, hence also our pooled parser
      * is not thread-safe.
      * <p>
      * <span style="color:red">INTERNAL API - SUBJECT TO CHANGE AT ANY TIME - USE AT YOUR OWN RISK.</span><br>
      */
     public static class PooledCSS3Parser extends CSS3Parser implements AutoCloseable {
         /**
          * The pool we want to return us to. Because multiple threads can use this, we
          * have to ensure that we see the action here.
          */
         private CSS3ParserPool pool_;
 
         /**
          * Create a new poolable parser.
          *
          * @param pool the pool the parser should return to when it is closed
          */
         protected PooledCSS3Parser(final CSS3ParserPool pool) {
             super();
             this.pool_ = pool;
         }
 
         /**
          * Resets the parser's pool state so it can be safely returned again.
          *
          * @param pool the pool the parser should return to when it is closed
          * @return this parser for fluid programming
          */
         protected PooledCSS3Parser markInUse(final CSS3ParserPool pool) {
             // ensure we detect programming mistakes
             if (this.pool_ == null) {
                 this.pool_ = pool;
             }
             else {
                 throw new IllegalStateException("This PooledParser was not returned to the pool properly");
             }
 
             return this;
         }
 
         /**
          * Implements the AutoClosable interface. The return method ensures that
          * we are notified when we incorrectly close it twice which indicates a
          * programming flow defect.
          *
          * @throws IllegalStateException in case the parser is closed several times
          */
         @Override
         public void close() {
             if (this.pool_ != null) {
                 final CSS3ParserPool oldPool = this.pool_;
                 // set null first and recycle later to avoid exposing a broken state
                 // volatile guarantees visibility
                 this.pool_ = null;
 
                 // return
                 oldPool.recycle(this);
             }
             else {
                 throw new IllegalStateException("This PooledParser was returned already");
             }
         }
     }
 }