xPath = createXPath(f -> {});
    }

    public XPath createXPath(final Consumer<XPathFactory> builder) {
        try {
            final XPathFactory factory = XPathFactory.newInstance();
            builder.accept(factory);
            return factory.newXPath();
        } catch (final Exception e) {
            throw new CrawlerSystemException("Failed to create XPath instance.", e);
        }
    }

    /**

            .put("CDN_LOOP", "CDN-Loop")
            .put("ETAG", "ETag")
            .put("SOURCE_MAP", "SourceMap")
            .put("SEC_CH_UA_WOW64", "Sec-CH-UA-WoW64")
            .put("SEC_WEBSOCKET_ACCEPT", "Sec-WebSocket-Accept")
            .put("SEC_WEBSOCKET_EXTENSIONS", "Sec-WebSocket-Extensions")
            .put("SEC_WEBSOCKET_KEY", "Sec-WebSocket-Key")
            .put("SEC_WEBSOCKET_PROTOCOL", "Sec-WebSocket-Protocol")

            .put("CDN_LOOP", "CDN-Loop")
            .put("ETAG", "ETag")
            .put("SOURCE_MAP", "SourceMap")
            .put("SEC_CH_UA_WOW64", "Sec-CH-UA-WoW64")
            .put("SEC_WEBSOCKET_ACCEPT", "Sec-WebSocket-Accept")
            .put("SEC_WEBSOCKET_EXTENSIONS", "Sec-WebSocket-Extensions")
            .put("SEC_WEBSOCKET_KEY", "Sec-WebSocket-Key")
            .put("SEC_WEBSOCKET_PROTOCOL", "Sec-WebSocket-Protocol")

* `allow_credentials` - 指示跨域请求支持 cookies。默认是 `False`。另外，允许凭证时 `allow_origins` 不能设定为 `['*']`，必须指定源。
* `expose_headers` - 指示可以被浏览器访问的响应头。默认为 `[]`。
* `max_age` - 设定浏览器缓存 CORS 响应的最长时间，单位是秒。默认为 `600`。

中间件响应两种特定类型的 HTTP 请求……

### CORS 预检请求

这是些带有 `Origin` 和 `Access-Control-Request-Method` 请求头的 `OPTIONS` 请求。

Contributing
============

Keeping the project small and stable limits our ability to accept new contributors. We are not
seeking new committers at this time, but some small contributions are welcome.

If you've found a security problem, please follow our [bug bounty][security] program.

If you've found a bug, please contribute a failing test case so we can study and fix it.

If you have a new feature idea, please build it in an external library. There are

Contributing
============

Keeping the project small and stable limits our ability to accept new contributors. We are not
seeking new committers at this time, but some small contributions are welcome.

If you've found a security problem, please follow our [bug bounty][security] program.

If you've found a bug, please contribute a failing test case so we can study and fix it.

If you have a new feature idea, please build it in an external library. There are

 * introduced in Unicode 3.1. One implication of this is that it rejects <a
 * href="http://www.unicode.org/versions/corrigendum1.html">"non-shortest form"</a> byte sequences,
 * even though the JDK decoder may accept them.
 *
 * @author Martin Buchholz
 * @author Clément Roux
 * @since 16.0
 */
@GwtCompatible(emulated = true)
@ElementTypesAreNonnullByDefault
public final class Utf8 {
  /**

                if (logger.isDebugEnabled()) {
                    logger.debug("role(lazy loading): {}", roleSet);
                }
                lazyLoading.accept(roleSet.toArray(new String[roleSet.size()]));
            }, 0, false);
        }

        return roles;
    }

            return; // basically no way when called in Framework (because called when SpecifyColumn exists)
        }
        __specifiedProperties = newModifiedProperties();
        __specifiedProperties.accept(__modifiedProperties);
    }

    // ===================================================================================
    //                                                                Specified Properties

  private fun run() {
    val serverSocket = ServerSocket(8888)
    serverSocket.reuseAddress = true
    while (true) {
      var socket: Socket? = null
      try {
        socket = serverSocket.accept()
        val sslSocket = doSsl(socket)
        val protocolString = Platform.get().getSelectedProtocol(sslSocket)
        val protocol = if (protocolString != null) get(protocolString) else null