public class ContextLoaderListener extends ContextLoader implements ServletContextListener {
    public void contextInitialized(ServletContextEvent event) {
		initWebApplicationContext(event.getServletContext());
	}
}

public class ContextLoader {
    public WebApplicationContext initWebApplicationContext(ServletContext servletContext) {
        // 1. WebApplicationContext 存在性的验证。
		if (servletContext.getAttribute(WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE) != null) {
            // web.xml 中存在多次 ContextLoader 定义
			throw new IllegalStateException(
					"Cannot initialize context because there is already a root application context present - " +
					"check whether you have multiple ContextLoader* definitions in your web.xml!");
		}

		servletContext.log("Initializing Spring root WebApplicationContext");
		Log logger = LogFactory.getLog(ContextLoader.class);
		if (logger.isInfoEnabled()) {
			logger.info("Root WebApplicationContext: initialization started");
		}
		long startTime = System.currentTimeMillis();

		try {
			// Store context in local instance variable, to guarantee that
			// it is available on ServletContext shutdown.
            // 初始化 context
			if (this.context == null) {
                // 2. 创建 WebApplicationContext 实例。  
				this.context = createWebApplicationContext(servletContext);
			}
			if (this.context instanceof ConfigurableWebApplicationContext) {
				ConfigurableWebApplicationContext cwac = (ConfigurableWebApplicationContext) this.context;
				if (!cwac.isActive()) {
					// The context has not yet been refreshed -> provide services such as
					// setting the parent context, setting the application context id, etc
					if (cwac.getParent() == null) {
						// The context instance was injected without an explicit parent ->
						// determine parent for root web application context, if any.
						ApplicationContext parent = loadParentContext(servletContext);
						cwac.setParent(parent);
					}
					configureAndRefreshWebApplicationContext(cwac, servletContext);
				}
			}
            // 3. 将实例记录在 servletContext 中。  
			servletContext.setAttribute(WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE, this.context);

			ClassLoader ccl = Thread.currentThread().getContextClassLoader();
			if (ccl == ContextLoader.class.getClassLoader()) {
				currentContext = this.context;
			}
			else if (ccl != null) {
                // 4. 映射当前的类加载器与创建的实例到全局变量 currentContextPerThread 中。
				currentContextPerThread.put(ccl, this.context);
			}

			if (logger.isInfoEnabled()) {
				long elapsedTime = System.currentTimeMillis() - startTime;
				logger.info("Root WebApplicationContext initialized in " + elapsedTime + " ms");
			}

			return this.context;
		}
		catch (RuntimeException | Error ex) {
			logger.error("Context initialization failed", ex);
			servletContext.setAttribute(WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE, ex);
			throw ex;
		}
	}
}

public class ContextLoader {
    // 文件在 spring-web 模块源码的 org.springframework.web.context 包下，内容如下
    // org.springframework.web.context.WebApplicationContext=org.springframework.web.context.support.XmlWebApplicationContext
    private static final String DEFAULT_STRATEGIES_PATH = "ContextLoader.properties";
    static {
		try {
			ClassPathResource resource = new ClassPathResource(DEFAULT_STRATEGIES_PATH, ContextLoader.class);
			defaultStrategies = PropertiesLoaderUtils.loadProperties(resource);
		}
		catch (IOException ex) {
			throw new IllegalStateException("Could not load 'ContextLoader.properties': " + ex.getMessage());
		}
	}
    
    protected WebApplicationContext createWebApplicationContext(ServletContext sc) {
		Class<?> contextClass = determineContextClass(sc);
		if (!ConfigurableWebApplicationContext.class.isAssignableFrom(contextClass)) {
			throw new ApplicationContextException("Custom context class [" + contextClass.getName() +
					"] is not of type [" + ConfigurableWebApplicationContext.class.getName() + "]");
		}
		return (ConfigurableWebApplicationContext) BeanUtils.instantiateClass(contextClass);
	}

    protected Class<?> determineContextClass(ServletContext servletContext) {
		String contextClassName = servletContext.getInitParameter(CONTEXT_CLASS_PARAM);
		if (contextClassName != null) {
			try {
				return ClassUtils.forName(contextClassName, ClassUtils.getDefaultClassLoader());
			}
			catch (ClassNotFoundException ex) {
				throw new ApplicationContextException(
						"Failed to load custom context class [" + contextClassName + "]", ex);
			}
		}
		else {
			contextClassName = defaultStrategies.getProperty(WebApplicationContext.class.getName());
			try {
				return ClassUtils.forName(contextClassName, ContextLoader.class.getClassLoader());
			}
			catch (ClassNotFoundException ex) {
				throw new ApplicationContextException(
						"Failed to load default context class [" + contextClassName + "]", ex);
			}
		}
	}
}

public abstract class HttpServletBean extends HttpServlet implements EnvironmentCapable, EnvironmentAware {
    public final void init() throws ServletException {

		// Set bean properties from init parameters.
        // 解析 init-param 并封装至 pvs 中
        // 1. 封装及验证初始化参数。 
		PropertyValues pvs = new ServletConfigPropertyValues(getServletConfig(), this.requiredProperties);
		if (!pvs.isEmpty()) {
			try {
                // 将当前的这个 sevlet 类转化为一个 BeanWrapper， 从而能够以 Spring 的方式来对 init-param 的值进行注入
				BeanWrapper bw = PropertyAccessorFactory.forBeanPropertyAccess(this);
				ResourceLoader resourceLoader = new ServletContextResourceLoader(getServletContext());
                // 注册自定义属性编辑器，一旦遇到 Resource 类型的属性将会使用 ResourceEditor 进行解析
				bw.registerCustomEditor(Resource.class, new ResourceEditor(resourceLoader, getEnvironment()));
                // 空实现，留给子类覆盖
				initBeanWrapper(bw);
                // 属性注入
				bw.setPropertyValues(pvs, true);
			}
			catch (BeansException ex) {
				if (logger.isErrorEnabled()) {
					logger.error("Failed to set bean properties on servlet '" + getServletName() + "'", ex);
				}
				throw ex;
			}
		}

		// 留给子类扩展 Let subclasses do whatever initialization they like.
		initServletBean();
	}
}

public abstract class HttpServletBean extends HttpServlet implements EnvironmentCapable, EnvironmentAware {
    private static class ServletConfigPropertyValues extends MutablePropertyValues {

		public ServletConfigPropertyValues(ServletConfig config, Set<String> requiredProperties)
				throws ServletException {

			Set<String> missingProps = (!CollectionUtils.isEmpty(requiredProperties) ?
					new HashSet<>(requiredProperties) : null);

			Enumeration<String> paramNames = config.getInitParameterNames();
			while (paramNames.hasMoreElements()) {
				String property = paramNames.nextElement();
				Object value = config.getInitParameter(property);
				addPropertyValue(new PropertyValue(property, value));
				if (missingProps != null) {
					missingProps.remove(property);
				}
			}

			// Fail if we are still missing properties.
			if (!CollectionUtils.isEmpty(missingProps)) {
				throw new ServletException(
						"Initialization from ServletConfig for servlet '" + config.getServletName() +
						"' failed; the following required properties were missing: " +
						StringUtils.collectionToDelimitedString(missingProps, ", "));
			}
		}
	}
}

public abstract class FrameworkServlet extends HttpServletBean implements ApplicationContextAware {
    protected final void initServletBean() throws ServletException {
		getServletContext().log("Initializing Spring " + getClass().getSimpleName() + " '" + getServletName() + "'");
		if (logger.isInfoEnabled()) {
			logger.info("Initializing Servlet '" + getServletName() + "'");
		}
		long startTime = System.currentTimeMillis();

		try {
            // 核心委托实现
			this.webApplicationContext = initWebApplicationContext();
            // 设计为子类覆盖
			initFrameworkServlet();
		}
		catch (ServletException | RuntimeException ex) {
			logger.error("Context initialization failed", ex);
			throw ex;
		}

		if (logger.isDebugEnabled()) {
			String value = this.enableLoggingRequestDetails ?
					"shown which may lead to unsafe logging of potentially sensitive data" :
					"masked to prevent unsafe logging of potentially sensitive data";
			logger.debug("enableLoggingRequestDetails='" + this.enableLoggingRequestDetails +
					"': request parameters and headers will be " + value);
		}

		if (logger.isInfoEnabled()) {
			logger.info("Completed initialization in " + (System.currentTimeMillis() - startTime) + " ms");
		}
	}
}

public abstract class FrameworkServlet extends HttpServletBean implements ApplicationContextAware {
    protected WebApplicationContext initWebApplicationContext() {
        // 1. 寻找或创建对应的 WebApplicationContext 实例
		WebApplicationContext rootContext =
				WebApplicationContextUtils.getWebApplicationContext(getServletContext());
		WebApplicationContext wac = null;

		if (this.webApplicationContext != null) {
			// A context instance was injected at construction time -> use it
			wac = this.webApplicationContext;
			if (wac instanceof ConfigurableWebApplicationContext) {
                // context 实例在构造函数中被注入
				ConfigurableWebApplicationContext cwac = (ConfigurableWebApplicationContext) wac;
				if (!cwac.isActive()) {
					// The context has not yet been refreshed -> provide services such as
					// setting the parent context, setting the application context id, etc
					if (cwac.getParent() == null) {
						// The context instance was injected without an explicit parent -> set
						// the root application context (if any; may be null) as the parent
						cwac.setParent(rootContext);
					}
                    // 刷新上下文环境
                    // 2. configureAndRefreshWebApplicationContext
					configureAndRefreshWebApplicationContext(cwac);
				}
			}
		}
		if (wac == null) {
            // 根据 contextAttribute 属性加载 WebApplicationContext
			wac = findWebApplicationContext();
		}
		if (wac == null) {
			// No context instance is defined for this servlet -> create a local one
			wac = createWebApplicationContext(rootContext);
		}

		if (!this.refreshEventReceived) {
			// Either the context is not a ConfigurableApplicationContext with refresh
			// support or the context injected at construction time had already been
			// refreshed -> trigger initial onRefresh manually here.
			synchronized (this.onRefreshMonitor) {
                // 3. 刷新
				onRefresh(wac);
			}
		}

		if (this.publishContext) {
			// Publish the context as a servlet context attribute.
			String attrName = getServletContextAttributeName();
			getServletContext().setAttribute(attrName, wac);
		}

		return wac;
	}
}

public abstract class FrameworkServlet extends HttpServletBean implements ApplicationContextAware {
    protected WebApplicationContext createWebApplicationContext(@Nullable WebApplicationContext parent) {
		return createWebApplicationContext((ApplicationContext) parent);
	}

    protected WebApplicationContext createWebApplicationContext(@Nullable ApplicationContext parent) {
        // 根据 servlet 的初始化参数 contextClass，如果没有配置默认为 XmlWebApplicationContext.class 
		Class<?> contextClass = getContextClass();
		if (!ConfigurableWebApplicationContext.class.isAssignableFrom(contextClass)) {
			throw new ApplicationContextException(
					"Fatal initialization error in servlet with name '" + getServletName() +
					"': custom WebApplicationContext class [" + contextClass.getName() +
					"] is not of type ConfigurableWebApplicationContext");
		}
        // 通过反射方式实例化 contextClass
		ConfigurableWebApplicationContext wac =
				(ConfigurableWebApplicationContext) BeanUtils.instantiateClass(contextClass);

		wac.setEnvironment(getEnvironment());
        // parent 为在 ContextLoaderListener 中创建的实例
        // 在 ContextLoaderListener 加载的时候初始化的 WebApplicationContext 类型实例
		wac.setParent(parent);
        // 获取 contextConfigLocation 属性，配置在 servlet 初始化参数中
		String configLocation = getContextConfigLocation();
		if (configLocation != null) {
			wac.setConfigLocation(configLocation);
		}
        // 初始化 Spring 环境包括加载配置文件等
		configureAndRefreshWebApplicationContext(wac);

		return wac;
	}
}

public abstract class FrameworkServlet extends HttpServletBean implements ApplicationContextAware {
    protected void configureAndRefreshWebApplicationContext(ConfigurableWebApplicationContext wac) {
		if (ObjectUtils.identityToString(wac).equals(wac.getId())) {
			// The application context id is still set to its original default value
			// -> assign a more useful id based on available information
			if (this.contextId != null) {
				wac.setId(this.contextId);
			}
			else {
				// Generate default id...
				wac.setId(ConfigurableWebApplicationContext.APPLICATION_CONTEXT_ID_PREFIX +
						ObjectUtils.getDisplayString(getServletContext().getContextPath()) + '/' + getServletName());
			}
		}

		wac.setServletContext(getServletContext());
		wac.setServletConfig(getServletConfig());
		wac.setNamespace(getNamespace());
		wac.addApplicationListener(new SourceFilteringListener(wac, new ContextRefreshListener()));

		// The wac environment's #initPropertySources will be called in any case when the context
		// is refreshed; do it eagerly here to ensure servlet property sources are in place for
		// use in any post-processing or initialization that occurs below prior to #refresh
		ConfigurableEnvironment env = wac.getEnvironment();
		if (env instanceof ConfigurableWebEnvironment) {
			((ConfigurableWebEnvironment) env).initPropertySources(getServletContext(), getServletConfig());
		}

		postProcessWebApplicationContext(wac);
		applyInitializers(wac);
        // 加载配置文件及整合 parent 到 wac，无论哪种方式一定会执行
		wac.refresh();
	}
}

public abstract class FrameworkServlet extends HttpServletBean implements ApplicationContextAware {
	protected final void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		processRequest(request, response);
	}

	protected final void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		processRequest(request, response);
	}

	/**
	 * 对于不同的方法，Spring 并没有做特殊处理，而是统一将程序再一次地引导至 processRequest 中
	 */
	protected final void processRequest(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		// 记录当前时间，用于计算 web 请求的处理时间
		long startTime = System.currentTimeMillis();
		Throwable failureCause = null;

		// 1. 为了保证当前线程的 LocaleContext 以及 RequestAttributes 可以在当前请求后还能恢复，提取当前线程的两个属性。
		// 2. 根据当前 request 创建对应的 LocaleContext 和 RequestAttributes，并绑定到当前线程。
		LocaleContext previousLocaleContext = LocaleContextHolder.getLocaleContext();
		LocaleContext localeContext = buildLocaleContext(request);

		RequestAttributes previousAttributes = RequestContextHolder.getRequestAttributes();
		ServletRequestAttributes requestAttributes = buildRequestAttributes(request, response, previousAttributes);

		WebAsyncManager asyncManager = WebAsyncUtils.getAsyncManager(request);
		asyncManager.registerCallableInterceptor(FrameworkServlet.class.getName(), new RequestBindingInterceptor());

		initContextHolders(request, localeContext, requestAttributes);

		try {
			// 3. 委托给 doService 方法进一步处理。
			doService(request, response);
		}
		catch (ServletException | IOException ex) {
			failureCause = ex;
			throw ex;
		}
		catch (Throwable ex) {
			failureCause = ex;
			throw new NestedServletException("Request processing failed", ex);
		}

		finally {
			// 4. 请求处理结束后恢复线程到原始状态。
			resetContextHolders(request, previousLocaleContext, previousAttributes);
			if (requestAttributes != null) {
				requestAttributes.requestCompleted();
			}
			logResult(request, response, failureCause, asyncManager);
			// 5. 请求处理结束后无论成功与否发布时间通知。
			publishRequestHandledEvent(request, response, startTime, failureCause);
		}
	}
}

public class DispatcherServlet extends FrameworkServlet {
	protected void doService(HttpServletRequest request, HttpServletResponse response) throws Exception {
		logRequest(request);

		// Keep a snapshot of the request attributes in case of an include,
		// to be able to restore the original attributes after the include.
		Map<String, Object> attributesSnapshot = null;
		if (WebUtils.isIncludeRequest(request)) {
			attributesSnapshot = new HashMap<>();
			Enumeration<?> attrNames = request.getAttributeNames();
			while (attrNames.hasMoreElements()) {
				String attrName = (String) attrNames.nextElement();
				if (this.cleanupAfterInclude || attrName.startsWith(DEFAULT_STRATEGIES_PREFIX)) {
					attributesSnapshot.put(attrName, request.getAttribute(attrName));
				}
			}
		}

		// Make framework objects available to handlers and view objects.
		request.setAttribute(WEB_APPLICATION_CONTEXT_ATTRIBUTE, getWebApplicationContext());
		request.setAttribute(LOCALE_RESOLVER_ATTRIBUTE, this.localeResolver);
		request.setAttribute(THEME_RESOLVER_ATTRIBUTE, this.themeResolver);
		request.setAttribute(THEME_SOURCE_ATTRIBUTE, getThemeSource());

		if (this.flashMapManager != null) {
			FlashMap inputFlashMap = this.flashMapManager.retrieveAndUpdate(request, response);
			if (inputFlashMap != null) {
				request.setAttribute(INPUT_FLASH_MAP_ATTRIBUTE, Collections.unmodifiableMap(inputFlashMap));
			}
			request.setAttribute(OUTPUT_FLASH_MAP_ATTRIBUTE, new FlashMap());
			request.setAttribute(FLASH_MAP_MANAGER_ATTRIBUTE, this.flashMapManager);
		}

		try {
			doDispatch(request, response);
		}
		finally {
			if (!WebAsyncUtils.getAsyncManager(request).isConcurrentHandlingStarted()) {
				// Restore the original attribute snapshot, in case of an include.
				if (attributesSnapshot != null) {
					restoreAttributesAfterInclude(request, attributesSnapshot);
				}
			}
		}
	}
}

public class DispatcherServlet extends FrameworkServlet {
	protected void doDispatch(HttpServletRequest request, HttpServletResponse response) throws Exception {
		HttpServletRequest processedRequest = request;
		HandlerExecutionChain mappedHandler = null;
		boolean multipartRequestParsed = false;

		WebAsyncManager asyncManager = WebAsyncUtils.getAsyncManager(request);

		try {
			ModelAndView mv = null;
			Exception dispatchException = null;

			try {
				// 如果是 multipartContent 类型的 request 则转换 request 为 MultipartHttpServletRequest 类型的 request
				processedRequest = checkMultipart(request);
				multipartRequestParsed = (processedRequest != request);

				// Determine handler for the current request.
				// 根据 request 信息寻找对应的 Handler
				mappedHandler = getHandler(processedRequest);
				if (mappedHandler == null) {
					// 如果没有找到对应的 handler 则通过 response 反馈错误信息
					noHandlerFound(processedRequest, response);
					return;
				}

				// Determine handler adapter for the current request.
				// 根据当前的 handler 寻找对应的 HandlerAdapter 
				HandlerAdapter ha = getHandlerAdapter(mappedHandler.getHandler());

				// Process last-modified header, if supported by the handler.
				// 如果当前 handler 支持 last-modified 头处理
				String method = request.getMethod();
				boolean isGet = "GET".equals(method);
				if (isGet || "HEAD".equals(method)) {
					long lastModified = ha.getLastModified(request, mappedHandler.getHandler());
					if (new ServletWebRequest(request, response).checkNotModified(lastModified) && isGet) {
						return;
					}
				}
				// 拦截器的 preHandler 方法的调用
				if (!mappedHandler.applyPreHandle(processedRequest, response)) {
					return;
				}

				// Actually invoke the handler.
				// 真正的激活 handler 并返回视图
				mv = ha.handle(processedRequest, response, mappedHandler.getHandler());

				if (asyncManager.isConcurrentHandlingStarted()) {
					return;
				}

				applyDefaultViewName(processedRequest, mv);
				// 应用所有拦截器的 posthandler 方法
				mappedHandler.applyPostHandle(processedRequest, response, mv);
			}
			catch (Exception ex) {
				dispatchException = ex;
			}
			catch (Throwable err) {
				// As of 4.3, we're processing Errors thrown from handler methods as well,
				// making them available for @ExceptionHandler methods and other scenarios.
				dispatchException = new NestedServletException("Handler dispatch failed", err);
			}
			// 处理页面跳转、完成处理激活触发器等
			processDispatchResult(processedRequest, response, mappedHandler, mv, dispatchException);
		}
		catch (Exception ex) {
			triggerAfterCompletion(processedRequest, response, mappedHandler, ex);
		}
		catch (Throwable err) {
			triggerAfterCompletion(processedRequest, response, mappedHandler,
					new NestedServletException("Handler processing failed", err));
		}
		finally {
			if (asyncManager.isConcurrentHandlingStarted()) {
				// Instead of postHandle and afterCompletion
				if (mappedHandler != null) {
					mappedHandler.applyAfterConcurrentHandlingStarted(processedRequest, response);
				}
			}
			else {
				// Clean up any resources used by a multipart request.
				if (multipartRequestParsed) {
					cleanupMultipart(processedRequest);
				}
			}
		}
	}

	private void applyDefaultViewName(HttpServletRequest request, @Nullable ModelAndView mv) throws Exception {
		// 视图名称转换应用于需要添加前缀后缀的情况
		if (mv != null && !mv.hasView()) {
			String defaultViewName = getDefaultViewName(request);
			if (defaultViewName != null) {
				mv.setViewName(defaultViewName);
			}
		}
	}

	private void processDispatchResult(HttpServletRequest request, HttpServletResponse response,
			@Nullable HandlerExecutionChain mappedHandler, @Nullable ModelAndView mv,
			@Nullable Exception exception) throws Exception {

		boolean errorView = false;

		if (exception != null) {
			if (exception instanceof ModelAndViewDefiningException) {
				logger.debug("ModelAndViewDefiningException encountered", exception);
				mv = ((ModelAndViewDefiningException) exception).getModelAndView();
			}
			else {
				Object handler = (mappedHandler != null ? mappedHandler.getHandler() : null);
				mv = processHandlerException(request, response, handler, exception);
				errorView = (mv != null);
			}
		}

		// Did the handler return a view to render?
		// 如果在 Handler 实例的处理中返回了 view，那么需要做页面的处理
		if (mv != null && !mv.wasCleared()) {
			// 处理页面跳转
			render(mv, request, response);
			if (errorView) {
				WebUtils.clearErrorRequestAttributes(request);
			}
		}
		else {
			if (logger.isTraceEnabled()) {
				logger.trace("No view rendering, null ModelAndView returned.");
			}
		}

		if (WebAsyncUtils.getAsyncManager(request).isConcurrentHandlingStarted()) {
			// Concurrent handling started during a forward
			return;
		}

		if (mappedHandler != null) {
			// Exception (if any) is already handled..
			// 完成处理激活触发器
			mappedHandler.triggerAfterCompletion(request, response, null);
		}
	}
}

public class HandlerExecutionChain {
	boolean applyPreHandle(HttpServletRequest request, HttpServletResponse response) throws Exception {
		HandlerInterceptor[] interceptors = getInterceptors();
		if (!ObjectUtils.isEmpty(interceptors)) {
			for (int i = 0; i < interceptors.length; i++) {
				HandlerInterceptor interceptor = interceptors[i];
				if (!interceptor.preHandle(request, response, this.handler)) {
					triggerAfterCompletion(request, response, null);
					return false;
				}
				this.interceptorIndex = i;
			}
		}
		return true;
	}

	void applyPostHandle(HttpServletRequest request, HttpServletResponse response, @Nullable ModelAndView mv)
			throws Exception {

		HandlerInterceptor[] interceptors = getInterceptors();
		if (!ObjectUtils.isEmpty(interceptors)) {
			for (int i = interceptors.length - 1; i >= 0; i--) {
				HandlerInterceptor interceptor = interceptors[i];
				interceptor.postHandle(request, response, this.handler, mv);
			}
		}
	}
}

public class DispatcherServlet extends FrameworkServlet {
	protected HttpServletRequest checkMultipart(HttpServletRequest request) throws MultipartException {
		if (this.multipartResolver != null && this.multipartResolver.isMultipart(request)) {
			if (WebUtils.getNativeRequest(request, MultipartHttpServletRequest.class) != null) {
				if (request.getDispatcherType().equals(DispatcherType.REQUEST)) {
					logger.trace("Request already resolved to MultipartHttpServletRequest, e.g. by MultipartFilter");
				}
			}
			else if (hasMultipartException(request)) {
				logger.debug("Multipart resolution previously failed for current request - " +
						"skipping re-resolution for undisturbed error rendering");
			}
			else {
				try {
					return this.multipartResolver.resolveMultipart(request);
				}
				catch (MultipartException ex) {
					if (request.getAttribute(WebUtils.ERROR_EXCEPTION_ATTRIBUTE) != null) {
						logger.debug("Multipart resolution failed for error dispatch", ex);
						// Keep processing error dispatch with regular request handle below
					}
					else {
						throw ex;
					}
				}
			}
		}
		// If not returned before: return original request.
		return request;
	}
}