@Nullable all the way: null-safety at field level

This commits extends nullability declarations to the field level, formalizing the interaction between methods and their underlying fields and therefore avoiding any nullability mismatch.

Issue: SPR-15720

spring-webmvc/src/main/java/org/springframework/web/servlet/DispatcherServlet.java

@@ -307,30 +307,39 @@ public class DispatcherServlet extends FrameworkServlet {
 	private boolean cleanupAfterInclude = true;
 
 	/** MultipartResolver used by this servlet */
+	@Nullable
 	private MultipartResolver multipartResolver;
 
 	/** LocaleResolver used by this servlet */
+	@Nullable
 	private LocaleResolver localeResolver;
 
 	/** ThemeResolver used by this servlet */
+	@Nullable
 	private ThemeResolver themeResolver;
 
 	/** List of HandlerMappings used by this servlet */
+	@Nullable
 	private List<HandlerMapping> handlerMappings;
 
 	/** List of HandlerAdapters used by this servlet */
+	@Nullable
 	private List<HandlerAdapter> handlerAdapters;
 
 	/** List of HandlerExceptionResolvers used by this servlet */
+	@Nullable
 	private List<HandlerExceptionResolver> handlerExceptionResolvers;
 
 	/** RequestToViewNameTranslator used by this servlet */
+	@Nullable
 	private RequestToViewNameTranslator viewNameTranslator;
 
 	/** FlashMapManager used by this servlet */
+	@Nullable
 	private FlashMapManager flashMapManager;
 
 	/** List of ViewResolvers used by this servlet */
+	@Nullable
 	private List<ViewResolver> viewResolvers;
 
 
@@ -893,12 +902,14 @@ public class DispatcherServlet extends FrameworkServlet {
 		request.setAttribute(THEME_RESOLVER_ATTRIBUTE, this.themeResolver);
 		request.setAttribute(THEME_SOURCE_ATTRIBUTE, getThemeSource());
 
-		FlashMap inputFlashMap = this.flashMapManager.retrieveAndUpdate(request, response);
-		if (inputFlashMap != null) {
-			request.setAttribute(INPUT_FLASH_MAP_ATTRIBUTE, Collections.unmodifiableMap(inputFlashMap));
+		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);
 		}
-		request.setAttribute(OUTPUT_FLASH_MAP_ATTRIBUTE, new FlashMap());
-		request.setAttribute(FLASH_MAP_MANAGER_ATTRIBUTE, this.flashMapManager);
 
 		try {
 			doDispatch(request, response);
@@ -941,7 +952,7 @@ public class DispatcherServlet extends FrameworkServlet {
 
 				// Determine handler for the current request.
 				mappedHandler = getHandler(processedRequest);
-				if (mappedHandler == null || mappedHandler.getHandler() == null) {
+				if (mappedHandler == null) {
 					noHandlerFound(processedRequest, response);
 					return;
 				}
@@ -1076,11 +1087,12 @@ public class DispatcherServlet extends FrameworkServlet {
 	 */
 	@Override
 	protected LocaleContext buildLocaleContext(final HttpServletRequest request) {
-		if (this.localeResolver instanceof LocaleContextResolver) {
-			return ((LocaleContextResolver) this.localeResolver).resolveLocaleContext(request);
+		LocaleResolver lr = this.localeResolver;
+		if (lr instanceof LocaleContextResolver) {
+			return ((LocaleContextResolver) lr).resolveLocaleContext(request);
 		}
 		else {
-			return () -> localeResolver.resolveLocale(request);
+			return () -> (lr != null ? lr.resolveLocale(request) : request.getLocale());
 		}
 	}
 
@@ -1140,10 +1152,12 @@ public class DispatcherServlet extends FrameworkServlet {
 	 * @see MultipartResolver#cleanupMultipart
 	 */
 	protected void cleanupMultipart(HttpServletRequest request) {
-		MultipartHttpServletRequest multipartRequest =
-				WebUtils.getNativeRequest(request, MultipartHttpServletRequest.class);
-		if (multipartRequest != null) {
-			this.multipartResolver.cleanupMultipart(multipartRequest);
+		if (this.multipartResolver != null) {
+			MultipartHttpServletRequest multipartRequest =
+					WebUtils.getNativeRequest(request, MultipartHttpServletRequest.class);
+			if (multipartRequest != null) {
+				this.multipartResolver.cleanupMultipart(multipartRequest);
+			}
 		}
 	}
 
@@ -1155,14 +1169,16 @@ public class DispatcherServlet extends FrameworkServlet {
 	 */
 	@Nullable
 	protected HandlerExecutionChain getHandler(HttpServletRequest request) throws Exception {
-		for (HandlerMapping hm : this.handlerMappings) {
-			if (logger.isTraceEnabled()) {
-				logger.trace(
-						"Testing handler map [" + hm + "] in DispatcherServlet with name '" + getServletName() + "'");
-			}
-			HandlerExecutionChain handler = hm.getHandler(request);
-			if (handler != null) {
-				return handler;
+		if (this.handlerMappings != null) {
+			for (HandlerMapping hm : this.handlerMappings) {
+				if (logger.isTraceEnabled()) {
+					logger.trace(
+							"Testing handler map [" + hm + "] in DispatcherServlet with name '" + getServletName() + "'");
+				}
+				HandlerExecutionChain handler = hm.getHandler(request);
+				if (handler != null) {
+					return handler;
+				}
 			}
 		}
 		return null;
@@ -1194,12 +1210,14 @@ public class DispatcherServlet extends FrameworkServlet {
 	 * @throws ServletException if no HandlerAdapter can be found for the handler. This is a fatal error.
 	 */
 	protected HandlerAdapter getHandlerAdapter(Object handler) throws ServletException {
-		for (HandlerAdapter ha : this.handlerAdapters) {
-			if (logger.isTraceEnabled()) {
-				logger.trace("Testing handler adapter [" + ha + "]");
-			}
-			if (ha.supports(handler)) {
-				return ha;
+		if (this.handlerAdapters != null) {
+			for (HandlerAdapter ha : this.handlerAdapters) {
+				if (logger.isTraceEnabled()) {
+					logger.trace("Testing handler adapter [" + ha + "]");
+				}
+				if (ha.supports(handler)) {
+					return ha;
+				}
 			}
 		}
 		throw new ServletException("No adapter for handler [" + handler +
@@ -1222,10 +1240,12 @@ public class DispatcherServlet extends FrameworkServlet {
 
 		// Check registered HandlerExceptionResolvers...
 		ModelAndView exMv = null;
-		for (HandlerExceptionResolver handlerExceptionResolver : this.handlerExceptionResolvers) {
-			exMv = handlerExceptionResolver.resolveException(request, response, handler, ex);
-			if (exMv != null) {
-				break;
+		if (this.handlerExceptionResolvers != null) {
+			for (HandlerExceptionResolver handlerExceptionResolver : this.handlerExceptionResolvers) {
+				exMv = handlerExceptionResolver.resolveException(request, response, handler, ex);
+				if (exMv != null) {
+					break;
+				}
 			}
 		}
 		if (exMv != null) {
@@ -1261,7 +1281,8 @@ public class DispatcherServlet extends FrameworkServlet {
 	 */
 	protected void render(ModelAndView mv, HttpServletRequest request, HttpServletResponse response) throws Exception {
 		// Determine locale for request and apply it to the response.
-		Locale locale = this.localeResolver.resolveLocale(request);
+		Locale locale =
+				(this.localeResolver != null ? this.localeResolver.resolveLocale(request) : request.getLocale());
 		response.setLocale(locale);
 
 		View view;
@@ -1310,7 +1331,7 @@ public class DispatcherServlet extends FrameworkServlet {
 	 */
 	@Nullable
 	protected String getDefaultViewName(HttpServletRequest request) throws Exception {
-		return this.viewNameTranslator.getViewName(request);
+		return (this.viewNameTranslator != null ? this.viewNameTranslator.getViewName(request) : null);
 	}
 
 	/**
@@ -1331,10 +1352,12 @@ public class DispatcherServlet extends FrameworkServlet {
 	protected View resolveViewName(String viewName, @Nullable Map<String, Object> model,
 			Locale locale, HttpServletRequest request) throws Exception {
 
-		for (ViewResolver viewResolver : this.viewResolvers) {
-			View view = viewResolver.resolveViewName(viewName, locale);
-			if (view != null) {
-				return view;
+		if (this.viewResolvers != null) {
+			for (ViewResolver viewResolver : this.viewResolvers) {
+				View view = viewResolver.resolveViewName(viewName, locale);
+				if (view != null) {
+					return view;
+				}
 			}
 		}
 		return null;

spring-webmvc/src/main/java/org/springframework/web/servlet/FlashMap.java

@@ -49,6 +49,7 @@ import org.springframework.util.StringUtils;
 @SuppressWarnings("serial")
 public final class FlashMap extends HashMap<String, Object> implements Comparable<FlashMap> {
 
+	@Nullable
 	private String targetRequestPath;
 
 	private final MultiValueMap<String, String> targetRequestParams = new LinkedMultiValueMap<>(4);
@@ -90,8 +91,8 @@ public final class FlashMap extends HashMap<String, Object> implements Comparabl
 
 	/**
 	 * Provide a request parameter identifying the request for this FlashMap.
-	 * @param name the expected parameter name (skipped if empty or {@code null})
-	 * @param value the expected value (skipped if empty or {@code null})
+	 * @param name the expected parameter name (skipped if empty)
+	 * @param value the expected value (skipped if empty)
 	 */
 	public FlashMap addTargetRequestParam(String name, String value) {
 		if (StringUtils.hasText(name) && StringUtils.hasText(value)) {

spring-webmvc/src/main/java/org/springframework/web/servlet/FrameworkServlet.java

@@ -164,18 +164,22 @@ public abstract class FrameworkServlet extends HttpServletBean implements Applic
 
 
 	/** ServletContext attribute to find the WebApplicationContext in */
+	@Nullable
 	private String contextAttribute;
 
 	/** WebApplicationContext implementation class to create */
 	private Class<?> contextClass = DEFAULT_CONTEXT_CLASS;
 
 	/** WebApplicationContext id to assign */
+	@Nullable
 	private String contextId;
 
 	/** Namespace for this servlet */
+	@Nullable
 	private String namespace;
 
 	/** Explicit context config location */
+	@Nullable
 	private String contextConfigLocation;
 
 	/** Actual ApplicationContextInitializer instances to apply to the context */
@@ -183,6 +187,7 @@ public abstract class FrameworkServlet extends HttpServletBean implements Applic
 			new ArrayList<>();
 
 	/** Comma-delimited ApplicationContextInitializer class names set through init param */
+	@Nullable
 	private String contextInitializerClasses;
 
 	/** Should we publish the context as a ServletContext attribute? */
@@ -201,6 +206,7 @@ public abstract class FrameworkServlet extends HttpServletBean implements Applic
 	private boolean dispatchTraceRequest = false;
 
 	/** WebApplicationContext for this servlet */
+	@Nullable
 	private WebApplicationContext webApplicationContext;
 
 	/** If the WebApplicationContext was injected via {@link #setApplicationContext} */
@@ -769,6 +775,7 @@ public abstract class FrameworkServlet extends HttpServletBean implements Applic
 	/**
 	 * Return this servlet's WebApplicationContext.
 	 */
+	@Nullable
 	public final WebApplicationContext getWebApplicationContext() {
 		return this.webApplicationContext;
 	}
@@ -1065,7 +1072,7 @@ public abstract class FrameworkServlet extends HttpServletBean implements Applic
 	private void publishRequestHandledEvent(HttpServletRequest request, HttpServletResponse response,
 			long startTime, @Nullable Throwable failureCause) {
 
-		if (this.publishEvents) {
+		if (this.publishEvents && this.webApplicationContext != null) {
 			// Whether or not we succeeded, publish an event.
 			long processingTime = System.currentTimeMillis() - startTime;
 			this.webApplicationContext.publishEvent(

spring-webmvc/src/main/java/org/springframework/web/servlet/HandlerExecutionChain.java

@@ -42,8 +42,10 @@ public class HandlerExecutionChain {
 
 	private final Object handler;
 
+	@Nullable
 	private HandlerInterceptor[] interceptors;
 
+	@Nullable
 	private List<HandlerInterceptor> interceptorList;
 
 	private int interceptorIndex = -1;
@@ -53,7 +55,7 @@ public class HandlerExecutionChain {
 	 * Create a new HandlerExecutionChain.
 	 * @param handler the handler object to execute
 	 */
-	public HandlerExecutionChain(@Nullable Object handler) {
+	public HandlerExecutionChain(Object handler) {
 		this(handler, (HandlerInterceptor[]) null);
 	}
 
@@ -63,7 +65,7 @@ public class HandlerExecutionChain {
 	 * @param interceptors the array of interceptors to apply
 	 * (in the given order) before the handler itself executes
 	 */
-	public HandlerExecutionChain(@Nullable Object handler, @Nullable HandlerInterceptor... interceptors) {
+	public HandlerExecutionChain(Object handler, @Nullable HandlerInterceptor... interceptors) {
 		if (handler instanceof HandlerExecutionChain) {
 			HandlerExecutionChain originalChain = (HandlerExecutionChain) handler;
 			this.handler = originalChain.getHandler();
@@ -80,9 +82,7 @@ public class HandlerExecutionChain {
 
 	/**
 	 * Return the handler object to execute.
-	 * @return the handler object (may be {@code null})
 	 */
-	@Nullable
 	public Object getHandler() {
 		return this.handler;
 	}
@@ -207,9 +207,6 @@ public class HandlerExecutionChain {
 	@Override
 	public String toString() {
 		Object handler = getHandler();
-		if (handler == null) {
-			return "HandlerExecutionChain with no handler";
-		}
 		StringBuilder sb = new StringBuilder();
 		sb.append("HandlerExecutionChain with handler [").append(handler).append("]");
 		HandlerInterceptor[] interceptors = getInterceptors();

spring-webmvc/src/main/java/org/springframework/web/servlet/HttpServletBean.java

@@ -84,6 +84,7 @@ public abstract class HttpServletBean extends HttpServlet implements Environment
 	/** Logger available to subclasses */
 	protected final Log logger = LogFactory.getLog(getClass());
 
+	@Nullable
 	private ConfigurableEnvironment environment;
 
 	private final Set<String> requiredProperties = new HashSet<>(4);

spring-webmvc/src/main/java/org/springframework/web/servlet/ModelAndView.java

@@ -47,12 +47,15 @@ import org.springframework.util.CollectionUtils;
 public class ModelAndView {
 
 	/** View instance or view name String */
+	@Nullable
 	private Object view;
 
 	/** Model Map */
+	@Nullable
 	private ModelMap model;
 
 	/** Optional HTTP status for the response */
+	@Nullable
 	private HttpStatus status;
 
 	/** Indicates whether or not this instance has been cleared with a call to {@link #clear()} */

spring-webmvc/src/main/java/org/springframework/web/servlet/RequestToViewNameTranslator.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -35,7 +35,7 @@ public interface RequestToViewNameTranslator {
 	 * Translate the given {@link HttpServletRequest} into a view name.
 	 * @param request the incoming {@link HttpServletRequest} providing
 	 * the context from which a view name is to be resolved
-	 * @return the view name (or {@code null} if no default found)
+	 * @return the view name, or {@code null} if no default found
 	 * @throws Exception if view name translation fails
 	 */
 	@Nullable

spring-webmvc/src/main/java/org/springframework/web/servlet/ResourceServlet.java

@@ -24,6 +24,7 @@ import javax.servlet.http.HttpServletResponse;
 
 import org.springframework.lang.Nullable;
 import org.springframework.util.AntPathMatcher;
+import org.springframework.util.Assert;
 import org.springframework.util.PathMatcher;
 import org.springframework.util.StringUtils;
 import org.springframework.web.context.support.ServletContextResource;
@@ -103,14 +104,18 @@ public class ResourceServlet extends HttpServletBean {
 	public static final String RESOURCE_PARAM_NAME = "resource";
 
 
+	@Nullable
 	private String defaultUrl;
 
+	@Nullable
 	private String allowedResources;
 
+	@Nullable
 	private String contentType;
 
 	private boolean applyLastModified = false;
 
+	@Nullable
 	private PathMatcher pathMatcher;
 
 	private long startupTime;
@@ -267,9 +272,12 @@ public class ResourceServlet extends HttpServletBean {
 			StringUtils.tokenizeToStringArray(resourceUrl, RESOURCE_URL_DELIMITERS);
 		for (String url : resourceUrls) {
 			// check whether URL matches allowed resources
-			if (this.allowedResources != null && !this.pathMatcher.match(this.allowedResources, url)) {
-				throw new ServletException("Resource [" + url +
-						"] does not match allowed pattern [" + this.allowedResources + "]");
+			if (this.allowedResources != null) {
+				Assert.state(this.pathMatcher != null, "No PathMatcher available");
+				if (!this.pathMatcher.match(this.allowedResources, url)) {
+					throw new ServletException("Resource [" + url +
+							"] does not match allowed pattern [" + this.allowedResources + "]");
+				}
 			}
 			if (logger.isDebugEnabled()) {
 				logger.debug("Including resource [" + url + "]");

spring-webmvc/src/main/java/org/springframework/web/servlet/config/annotation/ContentNegotiationConfigurer.java

@@ -96,8 +96,10 @@ public class ContentNegotiationConfigurer {
 	/**
 	 * Class constructor with {@link javax.servlet.ServletContext}.
 	 */
-	public ContentNegotiationConfigurer(ServletContext servletContext) {
-		this.factory.setServletContext(servletContext);
+	public ContentNegotiationConfigurer(@Nullable ServletContext servletContext) {
+		if (servletContext != null) {
+			this.factory.setServletContext(servletContext);
+		}
 	}
 
 

spring-webmvc/src/main/java/org/springframework/web/servlet/config/annotation/DefaultServletHandlerConfigurer.java

@@ -47,6 +47,7 @@ public class DefaultServletHandlerConfigurer {
 
 	private final ServletContext servletContext;
 
+	@Nullable
 	private DefaultServletHttpRequestHandler handler;
 
 

spring-webmvc/src/main/java/org/springframework/web/servlet/config/annotation/InterceptorRegistration.java

@@ -20,7 +20,7 @@ import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 
-import org.springframework.core.Ordered;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.PathMatcher;
 import org.springframework.util.StringUtils;
@@ -44,6 +44,7 @@ public class InterceptorRegistration {
 
 	private int order = 0;
 
+	@Nullable
 	private PathMatcher pathMatcher;
 
 

spring-webmvc/src/main/java/org/springframework/web/servlet/config/annotation/RedirectViewControllerRegistration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,6 +18,7 @@ package org.springframework.web.servlet.config.annotation;
 
 import org.springframework.context.ApplicationContext;
 import org.springframework.http.HttpStatus;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.web.servlet.mvc.ParameterizableViewController;
 import org.springframework.web.servlet.view.RedirectView;
@@ -49,7 +50,6 @@ public class RedirectViewControllerRegistration {
 
 	/**
 	 * Set the specific redirect 3xx status code to use.
-	 *
 	 * <p>If not set, {@link org.springframework.web.servlet.view.RedirectView}
 	 * will select {@code HttpStatus.MOVED_TEMPORARILY (302)} by default.
 	 */
@@ -63,7 +63,6 @@ public class RedirectViewControllerRegistration {
 	 * Whether to interpret a given redirect URL that starts with a slash ("/")
 	 * as relative to the current ServletContext, i.e. as relative to the web
 	 * application root.
-	 *
 	 * <p>Default is {@code true}.
 	 */
 	public RedirectViewControllerRegistration setContextRelative(boolean contextRelative) {
@@ -74,7 +73,6 @@ public class RedirectViewControllerRegistration {
 	/**
 	 * Whether to propagate the query parameters of the current request through
 	 * to the target redirect URL.
-	 *
 	 * <p>Default is {@code false}.
 	 */
 	public RedirectViewControllerRegistration setKeepQueryParams(boolean propagate) {
@@ -82,7 +80,7 @@ public class RedirectViewControllerRegistration {
 		return this;
 	}
 
-	protected void setApplicationContext(ApplicationContext applicationContext) {
+	protected void setApplicationContext(@Nullable ApplicationContext applicationContext) {
 		this.controller.setApplicationContext(applicationContext);
 		this.redirectView.setApplicationContext(applicationContext);
 	}

spring-webmvc/src/main/java/org/springframework/web/servlet/config/annotation/ResourceHandlerRegistration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -22,8 +22,9 @@ import java.util.List;
 import org.springframework.cache.Cache;
 import org.springframework.core.io.Resource;
 import org.springframework.core.io.ResourceLoader;
-import org.springframework.util.Assert;
 import org.springframework.http.CacheControl;
+import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 import org.springframework.web.servlet.resource.PathResourceResolver;
 import org.springframework.web.servlet.resource.ResourceHttpRequestHandler;
 
@@ -43,10 +44,13 @@ public class ResourceHandlerRegistration {
 
 	private final List<Resource> locations = new ArrayList<>();
 
+	@Nullable
 	private Integer cachePeriod;
 
+	@Nullable
 	private CacheControl cacheControl;
 
+	@Nullable
 	private ResourceChainRegistration resourceChainRegistration;
 
 

spring-webmvc/src/main/java/org/springframework/web/servlet/config/annotation/ResourceHandlerRegistry.java

@@ -56,6 +56,7 @@ public class ResourceHandlerRegistry {
 
 	private final ApplicationContext applicationContext;
 
+	@Nullable
 	private final ContentNegotiationManager contentNegotiationManager;
 
 	private final List<ResourceHandlerRegistration> registrations = new ArrayList<>();
@@ -142,9 +143,11 @@ public class ResourceHandlerRegistry {
 		for (ResourceHandlerRegistration registration : this.registrations) {
 			for (String pathPattern : registration.getPathPatterns()) {
 				ResourceHttpRequestHandler handler = registration.getRequestHandler();
+				if (this.contentNegotiationManager != null) {
+					handler.setContentNegotiationManager(this.contentNegotiationManager);
+				}
 				handler.setServletContext(this.servletContext);
 				handler.setApplicationContext(this.applicationContext);
-				handler.setContentNegotiationManager(this.contentNegotiationManager);
 				try {
 					handler.afterPropertiesSet();
 				}

spring-webmvc/src/main/java/org/springframework/web/servlet/config/annotation/ViewControllerRegistration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,6 +18,7 @@ package org.springframework.web.servlet.config.annotation;
 
 import org.springframework.context.ApplicationContext;
 import org.springframework.http.HttpStatus;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.web.servlet.RequestToViewNameTranslator;
 import org.springframework.web.servlet.mvc.ParameterizableViewController;
@@ -44,7 +45,6 @@ public class ViewControllerRegistration {
 
 	/**
 	 * Set the status code to set on the response. Optional.
-	 *
 	 * <p>If not set the response status will be 200 (OK).
 	 */
 	public ViewControllerRegistration setStatusCode(HttpStatus statusCode) {
@@ -54,19 +54,17 @@ public class ViewControllerRegistration {
 
 	/**
 	 * Set the view name to return. Optional.
-	 *
 	 * <p>If not specified, the view controller will return {@code null} as the
 	 * view name in which case the configured {@link RequestToViewNameTranslator}
 	 * will select the view name. The {@code DefaultRequestToViewNameTranslator}
 	 * for example translates "/foo/bar" to "foo/bar".
-	 *
 	 * @see org.springframework.web.servlet.view.DefaultRequestToViewNameTranslator
 	 */
 	public void setViewName(String viewName) {
 		this.controller.setViewName(viewName);
 	}
 
-	protected void setApplicationContext(ApplicationContext applicationContext) {
+	protected void setApplicationContext(@Nullable ApplicationContext applicationContext) {
 		this.controller.setApplicationContext(applicationContext);
 	}
 

spring-webmvc/src/main/java/org/springframework/web/servlet/config/annotation/ViewControllerRegistry.java

@@ -39,11 +39,11 @@ public class ViewControllerRegistry {
 
 	private final List<ViewControllerRegistration> registrations = new ArrayList<>(4);
 
-	private final List<RedirectViewControllerRegistration> redirectRegistrations =
-			new ArrayList<>(10);
+	private final List<RedirectViewControllerRegistration> redirectRegistrations = new ArrayList<>(10);
 
 	private int order = 1;
 
+	@Nullable
 	private ApplicationContext applicationContext;
 
 
@@ -97,7 +97,7 @@ public class ViewControllerRegistry {
 		this.order = order;
 	}
 
-	protected void setApplicationContext(ApplicationContext applicationContext) {
+	protected void setApplicationContext(@Nullable ApplicationContext applicationContext) {
 		this.applicationContext = applicationContext;
 	}
 

spring-webmvc/src/main/java/org/springframework/web/servlet/config/annotation/ViewResolverRegistry.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -25,6 +25,7 @@ import org.springframework.beans.factory.BeanFactoryUtils;
 import org.springframework.beans.factory.BeanInitializationException;
 import org.springframework.context.ApplicationContext;
 import org.springframework.core.Ordered;
+import org.springframework.lang.Nullable;
 import org.springframework.util.CollectionUtils;
 import org.springframework.util.ObjectUtils;
 import org.springframework.web.accept.ContentNegotiationManager;
@@ -53,14 +54,18 @@ import org.springframework.web.servlet.view.tiles3.TilesViewResolver;
  */
 public class ViewResolverRegistry {
 
+	@Nullable
 	private ContentNegotiatingViewResolver contentNegotiatingResolver;
 
 	private final List<ViewResolver> viewResolvers = new ArrayList<>(4);
 
+	@Nullable
 	private Integer order;
 
+	@Nullable
 	private ContentNegotiationManager contentNegotiationManager;
 
+	@Nullable
 	private ApplicationContext applicationContext;
 
 
@@ -98,15 +103,14 @@ public class ViewResolverRegistry {
 	 * media types requested by the client (e.g. in the Accept header).
 	 * <p>If invoked multiple times the provided default views will be added to
 	 * any other default views that may have been configured already.
-	 *
 	 * @see ContentNegotiatingViewResolver#setDefaultViews
 	 */
 	public void enableContentNegotiation(boolean useNotAcceptableStatus, View... defaultViews) {
-		initContentNegotiatingViewResolver(defaultViews);
-		this.contentNegotiatingResolver.setUseNotAcceptableStatusCode(useNotAcceptableStatus);
+		ContentNegotiatingViewResolver vr = initContentNegotiatingViewResolver(defaultViews);
+		vr.setUseNotAcceptableStatusCode(useNotAcceptableStatus);
 	}
 
-	private void initContentNegotiatingViewResolver(View[] defaultViews) {
+	private ContentNegotiatingViewResolver initContentNegotiatingViewResolver(View[] defaultViews) {
 		// ContentNegotiatingResolver in the registry: elevate its precedence!
 		this.order = (this.order != null ? this.order : Ordered.HIGHEST_PRECEDENCE);
 
@@ -123,8 +127,11 @@ public class ViewResolverRegistry {
 			this.contentNegotiatingResolver = new ContentNegotiatingViewResolver();
 			this.contentNegotiatingResolver.setDefaultViews(Arrays.asList(defaultViews));
 			this.contentNegotiatingResolver.setViewResolvers(this.viewResolvers);
-			this.contentNegotiatingResolver.setContentNegotiationManager(this.contentNegotiationManager);
+			if (this.contentNegotiationManager != null) {
+				this.contentNegotiatingResolver.setContentNegotiationManager(this.contentNegotiationManager);
+			}
 		}
+		return this.contentNegotiatingResolver;
 	}
 
 	/**
@@ -162,7 +169,7 @@ public class ViewResolverRegistry {
 	 * {@link org.springframework.web.servlet.view.tiles3.TilesConfigurer} bean.
 	 */
 	public UrlBasedViewResolverRegistration tiles() {
-		if (this.applicationContext != null && !hasBeanOfType(TilesConfigurer.class)) {
+		if (!checkBeanOfType(TilesConfigurer.class)) {
 			throw new BeanInitializationException("In addition to a Tiles view resolver " +
 					"there must also be a single TilesConfigurer bean in this web application context " +
 					"(or its parent).");
@@ -179,7 +186,7 @@ public class ViewResolverRegistry {
 	 * {@link org.springframework.web.servlet.view.freemarker.FreeMarkerConfigurer} bean.
 	 */
 	public UrlBasedViewResolverRegistration freeMarker() {
-		if (this.applicationContext != null && !hasBeanOfType(FreeMarkerConfigurer.class)) {
+		if (!checkBeanOfType(FreeMarkerConfigurer.class)) {
 			throw new BeanInitializationException("In addition to a FreeMarker view resolver " +
 					"there must also be a single FreeMarkerConfig bean in this web application context " +
 					"(or its parent): FreeMarkerConfigurer is the usual implementation. " +
@@ -195,7 +202,7 @@ public class ViewResolverRegistry {
 	 * prefix and a default suffix of ".tpl".
 	 */
 	public UrlBasedViewResolverRegistration groovy() {
-		if (this.applicationContext != null && !hasBeanOfType(GroovyMarkupConfigurer.class)) {
+		if (!checkBeanOfType(GroovyMarkupConfigurer.class)) {
 			throw new BeanInitializationException("In addition to a Groovy markup view resolver " +
 					"there must also be a single GroovyMarkupConfig bean in this web application context " +
 					"(or its parent): GroovyMarkupConfigurer is the usual implementation. " +
@@ -211,7 +218,7 @@ public class ViewResolverRegistry {
 	 * @since 4.2
 	 */
 	public UrlBasedViewResolverRegistration scriptTemplate() {
-		if (this.applicationContext != null && !hasBeanOfType(ScriptTemplateConfigurer.class)) {
+		if (!checkBeanOfType(ScriptTemplateConfigurer.class)) {
 			throw new BeanInitializationException("In addition to a script template view resolver " +
 					"there must also be a single ScriptTemplateConfig bean in this web application context " +
 					"(or its parent): ScriptTemplateConfigurer is the usual implementation. " +
@@ -262,11 +269,12 @@ public class ViewResolverRegistry {
 		this.order = order;
 	}
 
-	protected boolean hasBeanOfType(Class<?> beanType) {
-		return !ObjectUtils.isEmpty(BeanFactoryUtils.beanNamesForTypeIncludingAncestors(
-				this.applicationContext, beanType, false, false));
-	}
 
+	private boolean checkBeanOfType(Class<?> beanType) {
+		return (this.applicationContext == null ||
+				!ObjectUtils.isEmpty(BeanFactoryUtils.beanNamesForTypeIncludingAncestors(
+						this.applicationContext, beanType, false, false)));
+	}
 
 	protected int getOrder() {
 		return (this.order != null ? this.order : Ordered.LOWEST_PRECEDENCE);

spring-webmvc/src/main/java/org/springframework/web/servlet/config/annotation/WebMvcConfigurationSupport.java

@@ -25,8 +25,6 @@ import java.util.Map;
 import javax.servlet.ServletContext;
 import javax.servlet.http.HttpServletRequest;
 
-import com.fasterxml.jackson.databind.ObjectMapper;
-
 import org.springframework.beans.BeanUtils;
 import org.springframework.beans.factory.BeanFactoryUtils;
 import org.springframework.beans.factory.BeanInitializationException;
@@ -58,6 +56,7 @@ import org.springframework.http.converter.xml.MappingJackson2XmlHttpMessageConve
 import org.springframework.http.converter.xml.SourceHttpMessageConverter;
 import org.springframework.lang.Nullable;
 import org.springframework.util.AntPathMatcher;
+import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.PathMatcher;
 import org.springframework.validation.Errors;
@@ -198,22 +197,31 @@ public class WebMvcConfigurationSupport implements ApplicationContextAware, Serv
 			ClassUtils.isPresent("javax.json.bind.Jsonb", WebMvcConfigurationSupport.class.getClassLoader());
 
 
+	@Nullable
 	private ApplicationContext applicationContext;
 
+	@Nullable
 	private ServletContext servletContext;
 
+	@Nullable
 	private List<Object> interceptors;
 
+	@Nullable
 	private PathMatchConfigurer pathMatchConfigurer;
 
+	@Nullable
 	private ContentNegotiationManager contentNegotiationManager;
 
+	@Nullable
 	private List<HandlerMethodArgumentResolver> argumentResolvers;
 
+	@Nullable
 	private List<HandlerMethodReturnValueHandler> returnValueHandlers;
 
+	@Nullable
 	private List<HttpMessageConverter<?>> messageConverters;
 
+	@Nullable
 	private Map<String, CorsConfiguration> corsConfigurations;
 
 
@@ -229,7 +237,8 @@ public class WebMvcConfigurationSupport implements ApplicationContextAware, Serv
 	 * Return the associated Spring {@link ApplicationContext}.
 	 * @since 4.2
 	 */
-	public ApplicationContext getApplicationContext() {
+	@Nullable
+	public final ApplicationContext getApplicationContext() {
 		return this.applicationContext;
 	}
 
@@ -246,7 +255,8 @@ public class WebMvcConfigurationSupport implements ApplicationContextAware, Serv
 	 * Return the associated {@link javax.servlet.ServletContext}.
 	 * @since 4.2
 	 */
-	public ServletContext getServletContext() {
+	@Nullable
+	public final ServletContext getServletContext() {
 		return this.servletContext;
 	}
 
@@ -383,7 +393,7 @@ public class WebMvcConfigurationSupport implements ApplicationContextAware, Serv
 			try {
 				this.contentNegotiationManager = configurer.getContentNegotiationManager();
 			}
-			catch (Exception ex) {
+			catch (Throwable ex) {
 				throw new BeanInitializationException("Could not create ContentNegotiationManager", ex);
 			}
 		}
@@ -465,6 +475,9 @@ public class WebMvcConfigurationSupport implements ApplicationContextAware, Serv
 	 */
 	@Bean
 	public HandlerMapping resourceHandlerMapping() {
+		Assert.state(this.applicationContext != null, "No ApplicationContext set");
+		Assert.state(this.servletContext != null, "No ServletContext set");
+
 		ResourceHandlerRegistry registry = new ResourceHandlerRegistry(this.applicationContext,
 				this.servletContext, mvcContentNegotiationManager());
 		addResourceHandlers(registry);
@@ -514,7 +527,8 @@ public class WebMvcConfigurationSupport implements ApplicationContextAware, Serv
 	 */
 	@Bean
 	public HandlerMapping defaultServletHandlerMapping() {
-		DefaultServletHandlerConfigurer configurer = new DefaultServletHandlerConfigurer(servletContext);
+		Assert.state(this.servletContext != null, "No ServletContext set");
+		DefaultServletHandlerConfigurer configurer = new DefaultServletHandlerConfigurer(this.servletContext);
 		configureDefaultServletHandling(configurer);
 		AbstractHandlerMapping handlerMapping = configurer.getHandlerMapping();
 		handlerMapping = handlerMapping != null ? handlerMapping : new EmptyHandlerMapping();
@@ -785,16 +799,22 @@ public class WebMvcConfigurationSupport implements ApplicationContextAware, Serv
 		}
 
 		if (jackson2XmlPresent) {
-			ObjectMapper objectMapper = Jackson2ObjectMapperBuilder.xml().applicationContext(this.applicationContext).build();
-			messageConverters.add(new MappingJackson2XmlHttpMessageConverter(objectMapper));
+			Jackson2ObjectMapperBuilder builder = Jackson2ObjectMapperBuilder.xml();
+			if (this.applicationContext != null) {
+				builder.applicationContext(this.applicationContext);
+			}
+			messageConverters.add(new MappingJackson2XmlHttpMessageConverter(builder.build()));
 		}
 		else if (jaxb2Present) {
 			messageConverters.add(new Jaxb2RootElementHttpMessageConverter());
 		}
 
 		if (jackson2Present) {
-			ObjectMapper objectMapper = Jackson2ObjectMapperBuilder.json().applicationContext(this.applicationContext).build();
-			messageConverters.add(new MappingJackson2HttpMessageConverter(objectMapper));
+			Jackson2ObjectMapperBuilder builder = Jackson2ObjectMapperBuilder.json();
+			if (this.applicationContext != null) {
+				builder.applicationContext(this.applicationContext);
+			}
+			messageConverters.add(new MappingJackson2HttpMessageConverter(builder.build()));
 		}
 		else if (gsonPresent) {
 			messageConverters.add(new GsonHttpMessageConverter());
@@ -804,12 +824,18 @@ public class WebMvcConfigurationSupport implements ApplicationContextAware, Serv
 		}
 
 		if (jackson2SmilePresent) {
-			ObjectMapper objectMapper = Jackson2ObjectMapperBuilder.smile().applicationContext(this.applicationContext).build();
-			messageConverters.add(new MappingJackson2SmileHttpMessageConverter(objectMapper));
+			Jackson2ObjectMapperBuilder builder = Jackson2ObjectMapperBuilder.smile();
+			if (this.applicationContext != null) {
+				builder.applicationContext(this.applicationContext);
+			}
+			messageConverters.add(new MappingJackson2SmileHttpMessageConverter(builder.build()));
 		}
 		if (jackson2CborPresent) {
-			ObjectMapper objectMapper = Jackson2ObjectMapperBuilder.cbor().applicationContext(this.applicationContext).build();
-			messageConverters.add(new MappingJackson2CborHttpMessageConverter(objectMapper));
+			Jackson2ObjectMapperBuilder builder = Jackson2ObjectMapperBuilder.cbor();
+			if (this.applicationContext != null) {
+				builder.applicationContext(this.applicationContext);
+			}
+			messageConverters.add(new MappingJackson2CborHttpMessageConverter(builder.build()));
 		}
 	}
 
@@ -911,7 +937,9 @@ public class WebMvcConfigurationSupport implements ApplicationContextAware, Serv
 			exceptionHandlerResolver.setResponseBodyAdvice(
 					Collections.singletonList(new JsonViewResponseBodyAdvice()));
 		}
-		exceptionHandlerResolver.setApplicationContext(this.applicationContext);
+		if (this.applicationContext != null) {
+			exceptionHandlerResolver.setApplicationContext(this.applicationContext);
+		}
 		exceptionHandlerResolver.afterPropertiesSet();
 		exceptionResolvers.add(exceptionHandlerResolver);
 
@@ -947,7 +975,9 @@ public class WebMvcConfigurationSupport implements ApplicationContextAware, Serv
 	public ViewResolver mvcViewResolver() {
 		ViewResolverRegistry registry = new ViewResolverRegistry();
 		registry.setContentNegotiationManager(mvcContentNegotiationManager());
-		registry.setApplicationContext(this.applicationContext);
+		if (this.applicationContext != null) {
+			registry.setApplicationContext(this.applicationContext);
+		}
 		configureViewResolvers(registry);
 
 		if (registry.getViewResolvers().isEmpty()) {
@@ -962,7 +992,9 @@ public class WebMvcConfigurationSupport implements ApplicationContextAware, Serv
 		composite.setOrder(registry.getOrder());
 		composite.setViewResolvers(registry.getViewResolvers());
 		composite.setApplicationContext(this.applicationContext);
-		composite.setServletContext(this.servletContext);
+		if (this.servletContext != null) {
+			composite.setServletContext(this.servletContext);
+		}
 		return composite;
 	}
 

spring-webmvc/src/main/java/org/springframework/web/servlet/handler/AbstractHandlerExceptionResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -51,10 +51,13 @@ public abstract class AbstractHandlerExceptionResolver implements HandlerExcepti
 
 	private int order = Ordered.LOWEST_PRECEDENCE;
 
+	@Nullable
 	private Set<?> mappedHandlers;
 
+	@Nullable
 	private Class<?>[] mappedHandlerClasses;
 
+	@Nullable
 	private Log warnLogger;
 
 	private boolean preventResponseCaching = false;
@@ -101,7 +104,6 @@ public abstract class AbstractHandlerExceptionResolver implements HandlerExcepti
 	 * <p>Default is no warn logging. Specify this setting to activate warn logging into a specific
 	 * category. Alternatively, override the {@link #logException} method for custom logging.
 	 * @see org.apache.commons.logging.LogFactory#getLog(String)
-	 * @see org.apache.log4j.Logger#getLogger(String)
 	 * @see java.util.logging.Logger#getLogger(String)
 	 */
 	public void setWarnLogCategory(String loggerName) {

spring-webmvc/src/main/java/org/springframework/web/servlet/handler/AbstractHandlerMapping.java

@@ -69,6 +69,7 @@ public abstract class AbstractHandlerMapping extends WebApplicationObjectSupport
 
 	private int order = Integer.MAX_VALUE;  // default: same as non-Ordered
 
+	@Nullable
 	private Object defaultHandler;
 
 	private UrlPathHelper urlPathHelper = new UrlPathHelper();
@@ -481,6 +482,7 @@ public abstract class AbstractHandlerMapping extends WebApplicationObjectSupport
 
 	private class PreFlightHandler implements HttpRequestHandler, CorsConfigurationSource {
 
+		@Nullable
 		private final CorsConfiguration config;
 
 		public PreFlightHandler(@Nullable CorsConfiguration config) {
@@ -501,6 +503,7 @@ public abstract class AbstractHandlerMapping extends WebApplicationObjectSupport
 
 	private class CorsInterceptor extends HandlerInterceptorAdapter implements CorsConfigurationSource {
 
+		@Nullable
 		private final CorsConfiguration config;
 
 		public CorsInterceptor(@Nullable CorsConfiguration config) {

spring-webmvc/src/main/java/org/springframework/web/servlet/handler/AbstractHandlerMethodMapping.java

@@ -88,6 +88,7 @@ public abstract class AbstractHandlerMethodMapping<T> extends AbstractHandlerMap
 
 	private boolean detectHandlerMethodsInAncestorContexts = false;
 
+	@Nullable
 	private HandlerMethodMappingNamingStrategy<T> namingStrategy;
 
 	private final MappingRegistry mappingRegistry = new MappingRegistry();
@@ -683,6 +684,7 @@ public abstract class AbstractHandlerMethodMapping<T> extends AbstractHandlerMap
 
 		private final List<String> directUrls;
 
+		@Nullable
 		private final String mappingName;
 
 		public MappingRegistration(T mapping, HandlerMethod handlerMethod,

spring-webmvc/src/main/java/org/springframework/web/servlet/handler/HandlerExceptionResolverComposite.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -34,18 +34,11 @@ import org.springframework.web.servlet.ModelAndView;
  */
 public class HandlerExceptionResolverComposite implements HandlerExceptionResolver, Ordered {
 
+	@Nullable
 	private List<HandlerExceptionResolver> resolvers;
 
 	private int order = Ordered.LOWEST_PRECEDENCE;
 
-	public void setOrder(int order) {
-		this.order = order;
-	}
-
-	@Override
-	public int getOrder() {
-		return this.order;
-	}
 
 	/**
 	 * Set the list of exception resolvers to delegate to.
@@ -58,21 +51,30 @@ public class HandlerExceptionResolverComposite implements HandlerExceptionResolv
 	 * Return the list of exception resolvers to delegate to.
 	 */
 	public List<HandlerExceptionResolver> getExceptionResolvers() {
-		return Collections.unmodifiableList(resolvers);
+		return (this.resolvers != null ? Collections.unmodifiableList(this.resolvers) : Collections.emptyList());
 	}
 
+	public void setOrder(int order) {
+		this.order = order;
+	}
+
+	@Override
+	public int getOrder() {
+		return this.order;
+	}
+
+
 	/**
 	 * Resolve the exception by iterating over the list of configured exception resolvers.
 	 * The first one to return a ModelAndView instance wins. Otherwise {@code null} is returned.
 	 */
 	@Override
 	@Nullable
-	public ModelAndView resolveException(HttpServletRequest request,
-										 HttpServletResponse response,
-										 @Nullable Object handler,
-										 Exception ex) {
-		if (resolvers != null) {
-			for (HandlerExceptionResolver handlerExceptionResolver : resolvers) {
+	public ModelAndView resolveException(HttpServletRequest request, HttpServletResponse response,
+			@Nullable Object handler,Exception ex) {
+
+		if (this.resolvers != null) {
+			for (HandlerExceptionResolver handlerExceptionResolver : this.resolvers) {
 				ModelAndView mav = handlerExceptionResolver.resolveException(request, response, handler, ex);
 				if (mav != null) {
 					return mav;

spring-webmvc/src/main/java/org/springframework/web/servlet/handler/MappedInterceptor.java

@@ -45,12 +45,15 @@ import org.springframework.web.servlet.ModelAndView;
  */
 public final class MappedInterceptor implements HandlerInterceptor {
 
+	@Nullable
 	private final String[] includePatterns;
 
+	@Nullable
 	private final String[] excludePatterns;
 
 	private final HandlerInterceptor interceptor;
 
+	@Nullable
 	private PathMatcher pathMatcher;
 
 

spring-webmvc/src/main/java/org/springframework/web/servlet/handler/SimpleMappingExceptionResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,7 +21,6 @@ import java.util.Enumeration;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Properties;
-
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 
@@ -49,16 +48,21 @@ public class SimpleMappingExceptionResolver extends AbstractHandlerExceptionReso
 	public static final String DEFAULT_EXCEPTION_ATTRIBUTE = "exception";
 
 
+	@Nullable
 	private Properties exceptionMappings;
 
+	@Nullable
 	private Class<?>[] excludedExceptions;
 
+	@Nullable
 	private String defaultErrorView;
 
+	@Nullable
 	private Integer defaultStatusCode;
 
 	private Map<String, Integer> statusCodes = new HashMap<>();
 
+	@Nullable
 	private String exceptionAttribute = DEFAULT_EXCEPTION_ATTRIBUTE;
 
 

spring-webmvc/src/main/java/org/springframework/web/servlet/handler/SimpleServletPostProcessor.java

@@ -69,8 +69,10 @@ public class SimpleServletPostProcessor implements
 
 	private boolean useSharedServletConfig = true;
 
+	@Nullable
 	private ServletContext servletContext;
 
+	@Nullable
 	private ServletConfig servletConfig;
 
 
@@ -140,9 +142,10 @@ public class SimpleServletPostProcessor implements
 
 		private final String servletName;
 
+		@Nullable
 		private final ServletContext servletContext;
 
-		public DelegatingServletConfig(String servletName, ServletContext servletContext) {
+		public DelegatingServletConfig(String servletName, @Nullable ServletContext servletContext) {
 			this.servletName = servletName;
 			this.servletContext = servletContext;
 		}
@@ -153,6 +156,7 @@ public class SimpleServletPostProcessor implements
 		}
 
 		@Override
+		@Nullable
 		public ServletContext getServletContext() {
 			return this.servletContext;
 		}

spring-webmvc/src/main/java/org/springframework/web/servlet/handler/UserRoleAuthorizationInterceptor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,6 +21,8 @@ import javax.servlet.ServletException;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 
+import org.springframework.lang.Nullable;
+
 /**
  * Interceptor that checks the authorization of the current user via the
  * user's roles, as evaluated by HttpServletRequest's isUserInRole method.
@@ -31,6 +33,7 @@ import javax.servlet.http.HttpServletResponse;
  */
 public class UserRoleAuthorizationInterceptor extends HandlerInterceptorAdapter {
 
+	@Nullable
 	private String[] authorizedRoles;
 
 

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/ServletForwardingController.java

@@ -23,6 +23,7 @@ import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 
 import org.springframework.beans.factory.BeanNameAware;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.web.servlet.ModelAndView;
 import org.springframework.web.util.WebUtils;
@@ -87,8 +88,10 @@ import org.springframework.web.util.WebUtils;
  */
 public class ServletForwardingController extends AbstractController implements BeanNameAware {
 
+	@Nullable
 	private String servletName;
 
+	@Nullable
 	private String beanName;
 
 

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/ServletWrappingController.java

@@ -28,6 +28,7 @@ import org.springframework.beans.factory.BeanNameAware;
 import org.springframework.beans.factory.DisposableBean;
 import org.springframework.beans.factory.InitializingBean;
 import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 import org.springframework.util.ReflectionUtils;
 import org.springframework.web.servlet.ModelAndView;
 
@@ -84,14 +85,18 @@ import org.springframework.web.servlet.ModelAndView;
 public class ServletWrappingController extends AbstractController
 		implements BeanNameAware, InitializingBean, DisposableBean {
 
+	@Nullable
 	private Class<? extends Servlet> servletClass;
 
+	@Nullable
 	private String servletName;
 
 	private Properties initParameters = new Properties();
 
+	@Nullable
 	private String beanName;
 
+	@Nullable
 	private Servlet servletInstance;
 
 
@@ -156,6 +161,7 @@ public class ServletWrappingController extends AbstractController
 	protected ModelAndView handleRequestInternal(HttpServletRequest request, HttpServletResponse response)
 			throws Exception {
 
+		Assert.state(this.servletInstance != null, "No Servlet instance");
 		this.servletInstance.service(request, response);
 		return null;
 	}
@@ -167,7 +173,9 @@ public class ServletWrappingController extends AbstractController
 	 */
 	@Override
 	public void destroy() {
-		this.servletInstance.destroy();
+		if (this.servletInstance != null) {
+			this.servletInstance.destroy();
+		}
 	}
 
 
@@ -179,6 +187,7 @@ public class ServletWrappingController extends AbstractController
 	private class DelegatingServletConfig implements ServletConfig {
 
 		@Override
+		@Nullable
 		public String getServletName() {
 			return servletName;
 		}

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/annotation/ResponseStatusExceptionResolver.java

@@ -17,7 +17,6 @@
 package org.springframework.web.servlet.mvc.annotation;
 
 import java.io.IOException;
-
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 
@@ -56,6 +55,7 @@ import org.springframework.web.servlet.handler.AbstractHandlerExceptionResolver;
  */
 public class ResponseStatusExceptionResolver extends AbstractHandlerExceptionResolver implements MessageSourceAware {
 
+	@Nullable
 	private MessageSource messageSource;
 
 

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/condition/AbstractNameValueExpression.java

@@ -18,6 +18,8 @@ package org.springframework.web.servlet.mvc.condition;
 
 import javax.servlet.http.HttpServletRequest;
 
+import org.springframework.lang.Nullable;
+
 /**
  * Supports "name=value" style expressions as described in:
  * {@link org.springframework.web.bind.annotation.RequestMapping#params()} and
@@ -31,6 +33,7 @@ abstract class AbstractNameValueExpression<T> implements NameValueExpression<T>
 
 	protected final String name;
 
+	@Nullable
 	protected final T value;
 
 	protected final boolean isNegated;
@@ -40,12 +43,12 @@ abstract class AbstractNameValueExpression<T> implements NameValueExpression<T>
 		int separator = expression.indexOf('=');
 		if (separator == -1) {
 			this.isNegated = expression.startsWith("!");
-			this.name = isNegated ? expression.substring(1) : expression;
+			this.name = (this.isNegated ? expression.substring(1) : expression);
 			this.value = null;
 		}
 		else {
 			this.isNegated = (separator > 0) && (expression.charAt(separator - 1) == '!');
-			this.name = isNegated ? expression.substring(0, separator - 1) : expression.substring(0, separator);
+			this.name = (this.isNegated ? expression.substring(0, separator - 1) : expression.substring(0, separator));
 			this.value = parseValue(expression.substring(separator + 1));
 		}
 	}

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/condition/ConsumesRequestCondition.java

@@ -23,7 +23,6 @@ import java.util.Iterator;
 import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Set;
-
 import javax.servlet.http.HttpServletRequest;
 
 import org.springframework.http.InvalidMediaTypeException;
@@ -90,7 +89,7 @@ public final class ConsumesRequestCondition extends AbstractRequestCondition<Con
 		if (headers != null) {
 			for (String header : headers) {
 				HeaderExpression expr = new HeaderExpression(header);
-				if ("Content-Type".equalsIgnoreCase(expr.name)) {
+				if ("Content-Type".equalsIgnoreCase(expr.name) && expr.value != null) {
 					for (MediaType mediaType : MediaType.parseMediaTypes(expr.value)) {
 						result.add(new ConsumeMediaTypeExpression(mediaType, expr.isNegated));
 					}

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/condition/HeadersRequestCondition.java

@@ -22,6 +22,7 @@ import java.util.LinkedHashSet;
 import java.util.Set;
 import javax.servlet.http.HttpServletRequest;
 
+import org.springframework.util.ObjectUtils;
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.cors.CorsUtils;
 
@@ -156,12 +157,12 @@ public final class HeadersRequestCondition extends AbstractRequestCondition<Head
 
 		@Override
 		protected boolean matchName(HttpServletRequest request) {
-			return request.getHeader(name) != null;
+			return (request.getHeader(this.name) != null);
 		}
 
 		@Override
 		protected boolean matchValue(HttpServletRequest request) {
-			return value.equals(request.getHeader(name));
+			return ObjectUtils.nullSafeEquals(this.value, request.getHeader(this.name));
 		}
 	}
 

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/condition/NameValueExpression.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,6 +16,7 @@
 
 package org.springframework.web.servlet.mvc.condition;
 
+import org.springframework.lang.Nullable;
 import org.springframework.web.bind.annotation.RequestMapping;
 
 /**
@@ -24,7 +25,6 @@ import org.springframework.web.bind.annotation.RequestMapping;
  *
  * @author Rossen Stoyanchev
  * @since 3.1
- *
  * @see RequestMapping#params()
  * @see RequestMapping#headers()
  */
@@ -32,6 +32,7 @@ public interface NameValueExpression<T> {
 
 	String getName();
 
+	@Nullable
 	T getValue();
 
 	boolean isNegated();

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/condition/ParamsRequestCondition.java

@@ -22,6 +22,7 @@ import java.util.LinkedHashSet;
 import java.util.Set;
 import javax.servlet.http.HttpServletRequest;
 
+import org.springframework.util.ObjectUtils;
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.util.WebUtils;
 
@@ -141,12 +142,12 @@ public final class ParamsRequestCondition extends AbstractRequestCondition<Param
 
 		@Override
 		protected boolean matchName(HttpServletRequest request) {
-			return WebUtils.hasSubmitParameter(request, name);
+			return WebUtils.hasSubmitParameter(request, this.name);
 		}
 
 		@Override
 		protected boolean matchValue(HttpServletRequest request) {
-			return value.equals(request.getParameter(name));
+			return ObjectUtils.nullSafeEquals(this.value, request.getParameter(this.name));
 		}
 	}
 

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/condition/ProducesRequestCondition.java

@@ -114,7 +114,7 @@ public final class ProducesRequestCondition extends AbstractRequestCondition<Pro
 		if (headers != null) {
 			for (String header : headers) {
 				HeaderExpression expr = new HeaderExpression(header);
-				if ("Accept".equalsIgnoreCase(expr.name)) {
+				if ("Accept".equalsIgnoreCase(expr.name) && expr.value != null) {
 					for (MediaType mediaType : MediaType.parseMediaTypes(expr.value)) {
 						result.add(new ProduceMediaTypeExpression(mediaType, expr.isNegated));
 					}

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/condition/RequestConditionHolder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,7 +18,6 @@ package org.springframework.web.servlet.mvc.condition;
 
 import java.util.Collection;
 import java.util.Collections;
-
 import javax.servlet.http.HttpServletRequest;
 
 import org.springframework.lang.Nullable;
@@ -39,6 +38,7 @@ import org.springframework.lang.Nullable;
  */
 public final class RequestConditionHolder extends AbstractRequestCondition<RequestConditionHolder> {
 
+	@Nullable
 	private final RequestCondition<Object> condition;
 
 
@@ -87,7 +87,7 @@ public final class RequestConditionHolder extends AbstractRequestCondition<Reque
 			return this;
 		}
 		else {
-			assertEqualConditionTypes(other);
+			assertEqualConditionTypes(this.condition, other.condition);
 			RequestCondition<?> combined = (RequestCondition<?>) this.condition.combine(other.condition);
 			return new RequestConditionHolder(combined);
 		}
@@ -96,9 +96,9 @@ public final class RequestConditionHolder extends AbstractRequestCondition<Reque
 	/**
 	 * Ensure the held request conditions are of the same type.
 	 */
-	private void assertEqualConditionTypes(RequestConditionHolder other) {
-		Class<?> clazz = this.condition.getClass();
-		Class<?> otherClazz = other.condition.getClass();
+	private void assertEqualConditionTypes(RequestCondition<?> thisCondition, RequestCondition<?> otherCondition) {
+		Class<?> clazz = thisCondition.getClass();
+		Class<?> otherClazz = otherCondition.getClass();
 		if (!clazz.equals(otherClazz)) {
 			throw new ClassCastException("Incompatible request conditions: " + clazz + " and " + otherClazz);
 		}
@@ -135,7 +135,7 @@ public final class RequestConditionHolder extends AbstractRequestCondition<Reque
 			return -1;
 		}
 		else {
-			assertEqualConditionTypes(other);
+			assertEqualConditionTypes(this.condition, other.condition);
 			return this.condition.compareTo(other.condition, request);
 		}
 	}

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/RequestMappingInfo.java

@@ -53,6 +53,7 @@ import org.springframework.web.util.UrlPathHelper;
  */
 public final class RequestMappingInfo implements RequestCondition<RequestMappingInfo> {
 
+	@Nullable
 	private final String name;
 
 	private final PatternsRequestCondition patternsCondition;
@@ -418,8 +419,10 @@ public final class RequestMappingInfo implements RequestCondition<RequestMapping
 
 		private String[] produces = new String[0];
 
+		@Nullable
 		private String mappingName;
 
+		@Nullable
 		private RequestCondition<?> customCondition;
 
 		private BuilderConfiguration options = new BuilderConfiguration();
@@ -511,8 +514,10 @@ public final class RequestMappingInfo implements RequestCondition<RequestMapping
 	 */
 	public static class BuilderConfiguration {
 
+		@Nullable
 		private UrlPathHelper urlPathHelper;
 
+		@Nullable
 		private PathMatcher pathMatcher;
 
 		private boolean trailingSlashMatch = true;
@@ -521,6 +526,7 @@ public final class RequestMappingInfo implements RequestCondition<RequestMapping
 
 		private boolean registeredSuffixPatternMatch = false;
 
+		@Nullable
 		private ContentNegotiationManager contentNegotiationManager;
 
 		/**
@@ -614,7 +620,7 @@ public final class RequestMappingInfo implements RequestCondition<RequestMapping
 		 */
 		@Nullable
 		public List<String> getFileExtensions() {
-			if (useRegisteredSuffixPatternMatch() && getContentNegotiationManager() != null) {
+			if (useRegisteredSuffixPatternMatch() && this.contentNegotiationManager != null) {
 				return this.contentNegotiationManager.getAllFileExtensions();
 			}
 			return null;

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/AbstractMessageConverterMethodArgumentResolver.java

@@ -49,6 +49,7 @@ import org.springframework.http.converter.HttpMessageNotReadableException;
 import org.springframework.http.server.ServletServerHttpRequest;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
+import org.springframework.util.StreamUtils;
 import org.springframework.validation.Errors;
 import org.springframework.validation.annotation.Validated;
 import org.springframework.web.HttpMediaTypeNotSupportedException;
@@ -302,6 +303,7 @@ public abstract class AbstractMessageConverterMethodArgumentResolver implements
 
 		private final HttpHeaders headers;
 
+		@Nullable
 		private final InputStream body;
 
 		public EmptyBodyCheckingHttpInputMessage(HttpInputMessage inputMessage) throws IOException {
@@ -332,7 +334,7 @@ public abstract class AbstractMessageConverterMethodArgumentResolver implements
 
 		@Override
 		public InputStream getBody() {
-			return this.body;
+			return (this.body != null ? this.body : StreamUtils.emptyInput());
 		}
 
 		public boolean hasBody() {

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/AsyncTaskMethodReturnValueHandler.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -33,10 +33,11 @@ import org.springframework.web.method.support.ModelAndViewContainer;
  */
 public class AsyncTaskMethodReturnValueHandler implements HandlerMethodReturnValueHandler {
 
+	@Nullable
 	private final BeanFactory beanFactory;
 
 
-	public AsyncTaskMethodReturnValueHandler(BeanFactory beanFactory) {
+	public AsyncTaskMethodReturnValueHandler(@Nullable BeanFactory beanFactory) {
 		this.beanFactory = beanFactory;
 	}
 
@@ -56,7 +57,9 @@ public class AsyncTaskMethodReturnValueHandler implements HandlerMethodReturnVal
 		}
 
 		WebAsyncTask<?> webAsyncTask = (WebAsyncTask<?>) returnValue;
-		webAsyncTask.setBeanFactory(this.beanFactory);
+		if (this.beanFactory != null) {
+			webAsyncTask.setBeanFactory(this.beanFactory);
+		}
 		WebAsyncUtils.getAsyncManager(webRequest).startCallableProcessing(webAsyncTask, mavContainer);
 	}
 

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/ExceptionHandlerExceptionResolver.java

@@ -75,12 +75,16 @@ import org.springframework.web.servlet.support.RequestContextUtils;
 public class ExceptionHandlerExceptionResolver extends AbstractHandlerMethodExceptionResolver
 		implements ApplicationContextAware, InitializingBean {
 
+	@Nullable
 	private List<HandlerMethodArgumentResolver> customArgumentResolvers;
 
+	@Nullable
 	private HandlerMethodArgumentResolverComposite argumentResolvers;
 
+	@Nullable
 	private List<HandlerMethodReturnValueHandler> customReturnValueHandlers;
 
+	@Nullable
 	private HandlerMethodReturnValueHandlerComposite returnValueHandlers;
 
 	private List<HttpMessageConverter<?>> messageConverters;
@@ -89,6 +93,7 @@ public class ExceptionHandlerExceptionResolver extends AbstractHandlerMethodExce
 
 	private final List<Object> responseBodyAdvice = new ArrayList<>();
 
+	@Nullable
 	private ApplicationContext applicationContext;
 
 	private final Map<Class<?>, ExceptionHandlerMethodResolver> exceptionHandlerCache =
@@ -374,8 +379,12 @@ public class ExceptionHandlerExceptionResolver extends AbstractHandlerMethodExce
 			return null;
 		}
 
-		exceptionHandlerMethod.setHandlerMethodArgumentResolvers(this.argumentResolvers);
-		exceptionHandlerMethod.setHandlerMethodReturnValueHandlers(this.returnValueHandlers);
+		if (this.argumentResolvers != null) {
+			exceptionHandlerMethod.setHandlerMethodArgumentResolvers(this.argumentResolvers);
+		}
+		if (this.returnValueHandlers != null) {
+			exceptionHandlerMethod.setHandlerMethodReturnValueHandlers(this.returnValueHandlers);
+		}
 
 		ServletWebRequest webRequest = new ServletWebRequest(request, response);
 		ModelAndViewContainer mavContainer = new ModelAndViewContainer();

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/ExtendedServletRequestDataBinder.java

@@ -17,7 +17,6 @@
 package org.springframework.web.servlet.mvc.method.annotation;
 
 import java.util.Map;
-
 import javax.servlet.ServletRequest;
 
 import org.springframework.beans.MutablePropertyValues;
@@ -51,7 +50,7 @@ public class ExtendedServletRequestDataBinder extends ServletRequestDataBinder {
 	 * @param objectName the name of the target object
 	 * @see #DEFAULT_OBJECT_NAME
 	 */
-	public ExtendedServletRequestDataBinder(@Nullable Object target, @Nullable String objectName) {
+	public ExtendedServletRequestDataBinder(@Nullable Object target, String objectName) {
 		super(target, objectName);
 	}
 

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/ModelAndViewResolverMethodReturnValueHandler.java

@@ -55,6 +55,7 @@ import org.springframework.web.servlet.mvc.annotation.ModelAndViewResolver;
  */
 public class ModelAndViewResolverMethodReturnValueHandler implements HandlerMethodReturnValueHandler {
 
+	@Nullable
 	private final List<ModelAndViewResolver> mavResolvers;
 
 	private final ModelAttributeMethodProcessor modelAttributeProcessor = new ModelAttributeMethodProcessor(true);

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/MvcUriComponentsBuilder.java

@@ -717,21 +717,14 @@ public class MvcUriComponentsBuilder {
 	private static class ControllerMethodInvocationInterceptor
 			implements org.springframework.cglib.proxy.MethodInterceptor, MethodInterceptor {
 
-		private static final Method getControllerMethod =
-				ReflectionUtils.findMethod(MethodInvocationInfo.class, "getControllerMethod");
-
-		private static final Method getArgumentValues =
-				ReflectionUtils.findMethod(MethodInvocationInfo.class, "getArgumentValues");
-
-		private static final Method getControllerType =
-				ReflectionUtils.findMethod(MethodInvocationInfo.class, "getControllerType");
+		private final Class<?> controllerType;
 
+		@Nullable
 		private Method controllerMethod;
 
+		@Nullable
 		private Object[] argumentValues;
 
-		private Class<?> controllerType;
-
 		ControllerMethodInvocationInterceptor(Class<?> controllerType) {
 			this.controllerType = controllerType;
 		}
@@ -739,13 +732,13 @@ public class MvcUriComponentsBuilder {
 		@Override
 		@Nullable
 		public Object intercept(Object obj, Method method, Object[] args, @Nullable MethodProxy proxy) {
-			if (method.equals(getControllerMethod)) {
+			if (method.getName().equals("getControllerMethod")) {
 				return this.controllerMethod;
 			}
-			else if (method.equals(getArgumentValues)) {
+			else if (method.getName().equals("getArgumentValues")) {
 				return this.argumentValues;
 			}
-			else if (method.equals(getControllerType)) {
+			else if (method.getName().equals("getControllerType")) {
 				return this.controllerType;
 			}
 			else if (ReflectionUtils.isObjectMethod(method)) {

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/ReactiveTypeHandler.java

@@ -180,10 +180,12 @@ class ReactiveTypeHandler {
 
 		private final TaskExecutor taskExecutor;
 
+		@Nullable
 		private Subscription subscription;
 
 		private final AtomicReference<Object> elementRef = new AtomicReference<>();
 
+		@Nullable
 		private Throwable error;
 
 		private volatile boolean terminated;
@@ -219,7 +221,7 @@ class ReactiveTypeHandler {
 				terminate();
 				this.emitter.complete();
 			});
-			this.emitter.onError(t -> this.emitter.completeWithError(t));
+			this.emitter.onError(this.emitter::completeWithError);
 			subscription.request(1);
 		}
 
@@ -276,6 +278,7 @@ class ReactiveTypeHandler {
 			Object element = this.elementRef.get();
 			if (element != null) {
 				this.elementRef.lazySet(null);
+				Assert.state(this.subscription != null, "No subscription");
 				try {
 					send(element);
 					this.subscription.request(1);
@@ -317,7 +320,9 @@ class ReactiveTypeHandler {
 
 		private void terminate() {
 			this.done = true;
-			this.subscription.cancel();
+			if (this.subscription != null) {
+				this.subscription.cancel();
+			}
 		}
 
 	}

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/RedirectAttributesMethodArgumentResolver.java

@@ -59,8 +59,8 @@ public class RedirectAttributesMethodArgumentResolver implements HandlerMethodAr
 
 		ModelMap redirectAttributes;
 		if (binderFactory != null) {
-			DataBinder dataBinder = binderFactory.createBinder(webRequest, null, null);
-			redirectAttributes  = new RedirectAttributesModelMap(dataBinder);
+			DataBinder dataBinder = binderFactory.createBinder(webRequest, null, DataBinder.DEFAULT_OBJECT_NAME);
+			redirectAttributes = new RedirectAttributesModelMap(dataBinder);
 		}
 		else {
 			redirectAttributes  = new RedirectAttributesModelMap();

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/RequestMappingHandlerAdapter.java

@@ -116,16 +116,22 @@ import org.springframework.web.util.WebUtils;
 public class RequestMappingHandlerAdapter extends AbstractHandlerMethodAdapter
 		implements BeanFactoryAware, InitializingBean {
 
+	@Nullable
 	private List<HandlerMethodArgumentResolver> customArgumentResolvers;
 
+	@Nullable
 	private HandlerMethodArgumentResolverComposite argumentResolvers;
 
+	@Nullable
 	private HandlerMethodArgumentResolverComposite initBinderArgumentResolvers;
 
+	@Nullable
 	private List<HandlerMethodReturnValueHandler> customReturnValueHandlers;
 
+	@Nullable
 	private HandlerMethodReturnValueHandlerComposite returnValueHandlers;
 
+	@Nullable
 	private List<ModelAndViewResolver> modelAndViewResolvers;
 
 	private ContentNegotiationManager contentNegotiationManager = new ContentNegotiationManager();
@@ -134,10 +140,12 @@ public class RequestMappingHandlerAdapter extends AbstractHandlerMethodAdapter
 
 	private List<Object> requestResponseBodyAdvice = new ArrayList<>();
 
+	@Nullable
 	private WebBindingInitializer webBindingInitializer;
 
 	private AsyncTaskExecutor taskExecutor = new SimpleAsyncTaskExecutor("MvcAsync");
 
+	@Nullable
 	private Long asyncRequestTimeout;
 
 	private CallableProcessingInterceptor[] callableInterceptors = new CallableProcessingInterceptor[0];
@@ -156,21 +164,19 @@ public class RequestMappingHandlerAdapter extends AbstractHandlerMethodAdapter
 
 	private ParameterNameDiscoverer parameterNameDiscoverer = new DefaultParameterNameDiscoverer();
 
+	@Nullable
 	private ConfigurableBeanFactory beanFactory;
 
 
-	private final Map<Class<?>, SessionAttributesHandler> sessionAttributesHandlerCache =
-			new ConcurrentHashMap<>(64);
+	private final Map<Class<?>, SessionAttributesHandler> sessionAttributesHandlerCache = new ConcurrentHashMap<>(64);
 
 	private final Map<Class<?>, Set<Method>> initBinderCache = new ConcurrentHashMap<>(64);
 
-	private final Map<ControllerAdviceBean, Set<Method>> initBinderAdviceCache =
-			new LinkedHashMap<>();
+	private final Map<ControllerAdviceBean, Set<Method>> initBinderAdviceCache = new LinkedHashMap<>();
 
 	private final Map<Class<?>, Set<Method>> modelAttributeCache = new ConcurrentHashMap<>(64);
 
-	private final Map<ControllerAdviceBean, Set<Method>> modelAttributeAdviceCache =
-			new LinkedHashMap<>();
+	private final Map<ControllerAdviceBean, Set<Method>> modelAttributeAdviceCache = new LinkedHashMap<>();
 
 
 	public RequestMappingHandlerAdapter() {
@@ -284,7 +290,7 @@ public class RequestMappingHandlerAdapter extends AbstractHandlerMethodAdapter
 	 */
 	@Nullable
 	public List<HandlerMethodReturnValueHandler> getReturnValueHandlers() {
-		return this.returnValueHandlers.getHandlers();
+		return (this.returnValueHandlers != null ? this.returnValueHandlers.getHandlers() : null);
 	}
 
 	/**
@@ -310,7 +316,7 @@ public class RequestMappingHandlerAdapter extends AbstractHandlerMethodAdapter
 	 */
 	@Nullable
 	public List<ModelAndViewResolver> getModelAndViewResolvers() {
-		return modelAndViewResolvers;
+		return this.modelAndViewResolvers;
 	}
 
 	/**
@@ -827,8 +833,12 @@ public class RequestMappingHandlerAdapter extends AbstractHandlerMethodAdapter
 			ModelFactory modelFactory = getModelFactory(handlerMethod, binderFactory);
 
 			ServletInvocableHandlerMethod invocableMethod = createInvocableHandlerMethod(handlerMethod);
-			invocableMethod.setHandlerMethodArgumentResolvers(this.argumentResolvers);
-			invocableMethod.setHandlerMethodReturnValueHandlers(this.returnValueHandlers);
+			if (this.argumentResolvers != null) {
+				invocableMethod.setHandlerMethodArgumentResolvers(this.argumentResolvers);
+			}
+			if (this.returnValueHandlers != null) {
+				invocableMethod.setHandlerMethodReturnValueHandlers(this.returnValueHandlers);
+			}
 			invocableMethod.setDataBinderFactory(binderFactory);
 			invocableMethod.setParameterNameDiscoverer(this.parameterNameDiscoverer);
 
@@ -905,7 +915,9 @@ public class RequestMappingHandlerAdapter extends AbstractHandlerMethodAdapter
 
 	private InvocableHandlerMethod createModelAttributeMethod(WebDataBinderFactory factory, Object bean, Method method) {
 		InvocableHandlerMethod attrMethod = new InvocableHandlerMethod(bean, method);
-		attrMethod.setHandlerMethodArgumentResolvers(this.argumentResolvers);
+		if (this.argumentResolvers != null) {
+			attrMethod.setHandlerMethodArgumentResolvers(this.argumentResolvers);
+		}
 		attrMethod.setParameterNameDiscoverer(this.parameterNameDiscoverer);
 		attrMethod.setDataBinderFactory(factory);
 		return attrMethod;
@@ -937,7 +949,9 @@ public class RequestMappingHandlerAdapter extends AbstractHandlerMethodAdapter
 
 	private InvocableHandlerMethod createInitBinderMethod(Object bean, Method method) {
 		InvocableHandlerMethod binderMethod = new InvocableHandlerMethod(bean, method);
-		binderMethod.setHandlerMethodArgumentResolvers(this.initBinderArgumentResolvers);
+		if (this.initBinderArgumentResolvers != null) {
+			binderMethod.setHandlerMethodArgumentResolvers(this.initBinderArgumentResolvers);
+		}
 		binderMethod.setDataBinderFactory(new DefaultDataBinderFactory(this.webBindingInitializer));
 		binderMethod.setParameterNameDiscoverer(this.parameterNameDiscoverer);
 		return binderMethod;

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/RequestMappingHandlerMapping.java

@@ -64,6 +64,7 @@ public class RequestMappingHandlerMapping extends RequestMappingInfoHandlerMappi
 
 	private ContentNegotiationManager contentNegotiationManager = new ContentNegotiationManager();
 
+	@Nullable
 	private StringValueResolver embeddedValueResolver;
 
 	private RequestMappingInfo.BuilderConfiguration config = new RequestMappingInfo.BuilderConfiguration();

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/ResponseBodyEmitter.java

@@ -63,14 +63,17 @@ import org.springframework.util.ObjectUtils;
  */
 public class ResponseBodyEmitter {
 
+	@Nullable
 	private final Long timeout;
 
 	private final Set<DataWithMediaType> earlySendAttempts = new LinkedHashSet<>(8);
 
+	@Nullable
 	private Handler handler;
 
 	private boolean complete;
 
+	@Nullable
 	private Throwable failure;
 
 	private final DefaultCallback timeoutCallback = new DefaultCallback();
@@ -270,6 +273,7 @@ public class ResponseBodyEmitter {
 
 		private final Object data;
 
+		@Nullable
 		private final MediaType mediaType;
 
 		public DataWithMediaType(Object data, @Nullable MediaType mediaType) {
@@ -290,6 +294,7 @@ public class ResponseBodyEmitter {
 
 	private class DefaultCallback implements Runnable {
 
+		@Nullable
 		private Runnable delegate;
 
 		public void setDelegate(Runnable delegate) {
@@ -308,6 +313,7 @@ public class ResponseBodyEmitter {
 
 	private class ErrorCallback implements Consumer<Throwable> {
 
+		@Nullable
 		private Consumer<Throwable> delegate;
 
 		public void setDelegate(Consumer<Throwable> callback) {

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/ServletInvocableHandlerMethod.java

@@ -27,6 +27,7 @@ import org.springframework.core.MethodParameter;
 import org.springframework.core.ResolvableType;
 import org.springframework.http.HttpStatus;
 import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.StringUtils;
 import org.springframework.web.bind.annotation.ResponseBody;
@@ -60,6 +61,7 @@ public class ServletInvocableHandlerMethod extends InvocableHandlerMethod {
 
 	private static final Method CALLABLE_METHOD = ClassUtils.getMethod(Callable.class, "call");
 
+	@Nullable
 	private HandlerMethodReturnValueHandlerComposite returnValueHandlers;
 
 
@@ -112,6 +114,7 @@ public class ServletInvocableHandlerMethod extends InvocableHandlerMethod {
 		}
 
 		mavContainer.setRequestHandled(false);
+		Assert.state(this.returnValueHandlers != null, "No return value handlers");
 		try {
 			this.returnValueHandlers.handleReturnValue(
 					returnValue, getReturnValueType(returnValue), mavContainer, webRequest);
@@ -188,20 +191,19 @@ public class ServletInvocableHandlerMethod extends InvocableHandlerMethod {
 		private final MethodParameter returnType;
 
 		public ConcurrentResultHandlerMethod(final Object result, ConcurrentResultMethodParameter returnType) {
-			super(new Callable<Object>() {
-				@Override
-				public Object call() throws Exception {
-					if (result instanceof Exception) {
-						throw (Exception) result;
-					}
-					else if (result instanceof Throwable) {
-						throw new NestedServletException("Async processing failed", (Throwable) result);
-					}
-					return result;
+			super((Callable<Object>) () -> {
+				if (result instanceof Exception) {
+					throw (Exception) result;
 				}
+				else if (result instanceof Throwable) {
+					throw new NestedServletException("Async processing failed", (Throwable) result);
+				}
+				return result;
 			}, CALLABLE_METHOD);
 
-			setHandlerMethodReturnValueHandlers(ServletInvocableHandlerMethod.this.returnValueHandlers);
+			if (ServletInvocableHandlerMethod.this.returnValueHandlers != null) {
+				setHandlerMethodReturnValueHandlers(ServletInvocableHandlerMethod.this.returnValueHandlers);
+			}
 			this.returnType = returnType;
 		}
 
@@ -247,6 +249,7 @@ public class ServletInvocableHandlerMethod extends InvocableHandlerMethod {
 	 */
 	private class ConcurrentResultMethodParameter extends HandlerMethodParameter {
 
+		@Nullable
 		private final Object returnValue;
 
 		private final ResolvableType returnType;

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/ServletModelAttributeMethodProcessor.java

@@ -128,7 +128,7 @@ public class ServletModelAttributeMethodProcessor extends ModelAttributeMethodPr
 	 * @throws Exception
 	 */
 	@Nullable
-	protected Object createAttributeFromRequestValue(String sourceValue, @Nullable String attributeName,
+	protected Object createAttributeFromRequestValue(String sourceValue, String attributeName,
 			MethodParameter methodParam, WebDataBinderFactory binderFactory, NativeWebRequest request)
 			throws Exception {
 

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/ServletRequestDataBinderFactory.java

@@ -49,7 +49,7 @@ public class ServletRequestDataBinderFactory extends InitBinderDataBinderFactory
 	 */
 	@Override
 	protected ServletRequestDataBinder createBinderInstance(
-			@Nullable Object target, @Nullable String objectName, NativeWebRequest request) throws Exception  {
+			@Nullable Object target, String objectName, NativeWebRequest request) throws Exception  {
 
 		return new ExtendedServletRequestDataBinder(target, objectName);
 	}

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/ServletRequestMethodArgumentResolver.java

@@ -65,6 +65,7 @@ import org.springframework.web.servlet.support.RequestContextUtils;
  */
 public class ServletRequestMethodArgumentResolver implements HandlerMethodArgumentResolver {
 
+	@Nullable
 	private static final Method newPushBuilderMethod =
 			ClassUtils.getMethodIfAvailable(HttpServletRequest.class, "newPushBuilder");
 

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/SseEmitter.java

@@ -189,6 +189,7 @@ public class SseEmitter extends ResponseBodyEmitter {
 
 		private final Set<DataWithMediaType> dataToSend = new LinkedHashSet<>(4);
 
+		@Nullable
 		private StringBuilder sb;
 
 		@Override

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/support/RedirectAttributesModelMap.java

@@ -35,6 +35,7 @@ import org.springframework.validation.DataBinder;
 @SuppressWarnings("serial")
 public class RedirectAttributesModelMap extends ModelMap implements RedirectAttributes {
 
+	@Nullable
 	private final DataBinder dataBinder;
 
 	private final ModelMap flashAttributes = new ModelMap();

spring-webmvc/src/main/java/org/springframework/web/servlet/resource/AppCacheManifestTransformer.java

@@ -217,6 +217,7 @@ public class AppCacheManifestTransformer extends ResourceTransformerSupport {
 
 		private final String line;
 
+		@Nullable
 		private final Resource resource;
 
 		public LineOutput(String line, @Nullable Resource resource) {

spring-webmvc/src/main/java/org/springframework/web/servlet/resource/ResourceHttpRequestHandler.java

@@ -100,14 +100,19 @@ public class ResourceHttpRequestHandler extends WebContentGenerator
 
 	private final List<ResourceTransformer> resourceTransformers = new ArrayList<>(4);
 
+	@Nullable
 	private ResourceHttpMessageConverter resourceHttpMessageConverter;
 
+	@Nullable
 	private ResourceRegionHttpMessageConverter resourceRegionHttpMessageConverter;
 
+	@Nullable
 	private ContentNegotiationManager contentNegotiationManager;
 
+	@Nullable
 	private PathExtensionContentNegotiationStrategy contentNegotiationStrategy;
 
+	@Nullable
 	private CorsConfiguration corsConfiguration;
 
 
@@ -176,14 +181,15 @@ public class ResourceHttpRequestHandler extends WebContentGenerator
 	 * <p>By default a {@link ResourceHttpMessageConverter} will be configured.
 	 * @since 4.3
 	 */
-	public void setResourceHttpMessageConverter(ResourceHttpMessageConverter resourceHttpMessageConverter) {
-		this.resourceHttpMessageConverter = resourceHttpMessageConverter;
+	public void setResourceHttpMessageConverter(ResourceHttpMessageConverter messageConverter) {
+		this.resourceHttpMessageConverter = messageConverter;
 	}
 
 	/**
 	 * Return the configured resource converter.
 	 * @since 4.3
 	 */
+	@Nullable
 	public ResourceHttpMessageConverter getResourceHttpMessageConverter() {
 		return this.resourceHttpMessageConverter;
 	}
@@ -193,14 +199,15 @@ public class ResourceHttpRequestHandler extends WebContentGenerator
 	 * <p>By default a {@link ResourceRegionHttpMessageConverter} will be configured.
 	 * @since 4.3
 	 */
-	public void setResourceRegionHttpMessageConverter(ResourceRegionHttpMessageConverter resourceRegionHttpMessageConverter) {
-		this.resourceRegionHttpMessageConverter = resourceRegionHttpMessageConverter;
+	public void setResourceRegionHttpMessageConverter(ResourceRegionHttpMessageConverter messageConverter) {
+		this.resourceRegionHttpMessageConverter = messageConverter;
 	}
 
 	/**
 	 * Return the configured resource region converter.
 	 * @since 4.3
 	 */
+	@Nullable
 	public ResourceRegionHttpMessageConverter getResourceRegionHttpMessageConverter() {
 		return this.resourceRegionHttpMessageConverter;
 	}
@@ -368,10 +375,12 @@ public class ResourceHttpRequestHandler extends WebContentGenerator
 
 		ServletServerHttpResponse outputMessage = new ServletServerHttpResponse(response);
 		if (request.getHeader(HttpHeaders.RANGE) == null) {
+			Assert.state(this.resourceHttpMessageConverter != null, "Not initialized");
 			setHeaders(response, resource, mediaType);
 			this.resourceHttpMessageConverter.write(resource, mediaType, outputMessage);
 		}
 		else {
+			Assert.state(this.resourceRegionHttpMessageConverter != null, "Not initialized");
 			response.setHeader(HttpHeaders.ACCEPT_RANGES, "bytes");
 			ServletServerHttpRequest inputMessage = new ServletServerHttpRequest(request);
 			try {
@@ -516,7 +525,8 @@ public class ResourceHttpRequestHandler extends WebContentGenerator
 	 */
 	@Nullable
 	protected MediaType getMediaType(HttpServletRequest request, Resource resource) {
-		return this.contentNegotiationStrategy.getMediaTypeForResource(resource);
+		return (this.contentNegotiationStrategy != null ?
+				this.contentNegotiationStrategy.getMediaTypeForResource(resource) : null);
 	}
 
 	/**

spring-webmvc/src/main/java/org/springframework/web/servlet/resource/ResourceTransformerSupport.java

@@ -35,6 +35,7 @@ import org.springframework.util.StringUtils;
  */
 public abstract class ResourceTransformerSupport implements ResourceTransformer {
 
+	@Nullable
 	private ResourceUrlProvider resourceUrlProvider;
 
 
@@ -43,15 +44,15 @@ public abstract class ResourceTransformerSupport implements ResourceTransformer
 	 * URL of links in a transformed resource (e.g. import links in a CSS file).
 	 * This is required only for links expressed as full paths and not for
 	 * relative links.
-	 * @param resourceUrlProvider the URL provider to use
 	 */
 	public void setResourceUrlProvider(ResourceUrlProvider resourceUrlProvider) {
 		this.resourceUrlProvider = resourceUrlProvider;
 	}
 
 	/**
-	 * @return the configured {@code ResourceUrlProvider}.
+	 * Return the configured {@code ResourceUrlProvider}.
 	 */
+	@Nullable
 	public ResourceUrlProvider getResourceUrlProvider() {
 		return this.resourceUrlProvider;
 	}

spring-webmvc/src/main/java/org/springframework/web/servlet/resource/ResourceUrlEncodingFilter.java

@@ -66,9 +66,10 @@ public class ResourceUrlEncodingFilter extends GenericFilterBean {
 		private final HttpServletRequest request;
 
 		/* Cache the index and prefix of the path within the DispatcherServlet mapping */
+		@Nullable
 		private Integer indexLookupPath;
 
-		private String prefixLookupPath;
+		private String prefixLookupPath = "";
 
 		public ResourceUrlEncodingResponseWrapper(HttpServletRequest request, HttpServletResponse wrapped) {
 			super(wrapped);
@@ -83,11 +84,11 @@ public class ResourceUrlEncodingFilter extends GenericFilterBean {
 				return super.encodeURL(url);
 			}
 
-			initLookupPath(resourceUrlProvider);
+			int index = initLookupPath(resourceUrlProvider);
 			if (url.startsWith(this.prefixLookupPath)) {
 				int suffixIndex = getQueryParamsIndex(url);
 				String suffix = url.substring(suffixIndex);
-				String lookupPath = url.substring(this.indexLookupPath, suffixIndex);
+				String lookupPath = url.substring(index, suffixIndex);
 				lookupPath = resourceUrlProvider.getForLookupPath(lookupPath);
 				if (lookupPath != null) {
 					return super.encodeURL(this.prefixLookupPath + lookupPath + suffix);
@@ -103,14 +104,13 @@ public class ResourceUrlEncodingFilter extends GenericFilterBean {
 					ResourceUrlProviderExposingInterceptor.RESOURCE_URL_PROVIDER_ATTR);
 		}
 
-		private void initLookupPath(ResourceUrlProvider urlProvider) {
+		private int initLookupPath(ResourceUrlProvider urlProvider) {
 			if (this.indexLookupPath == null) {
 				UrlPathHelper pathHelper = urlProvider.getUrlPathHelper();
 				String requestUri = pathHelper.getRequestUri(this.request);
 				String lookupPath = pathHelper.getLookupPathForRequest(this.request);
 				this.indexLookupPath = requestUri.lastIndexOf(lookupPath);
 				this.prefixLookupPath = requestUri.substring(0, this.indexLookupPath);
-
 				if ("/".equals(lookupPath) && !"/".equals(requestUri)) {
 					String contextPath = pathHelper.getContextPath(this.request);
 					if (requestUri.equals(contextPath)) {
@@ -119,6 +119,7 @@ public class ResourceUrlEncodingFilter extends GenericFilterBean {
 					}
 				}
 			}
+			return this.indexLookupPath;
 		}
 
 		private int getQueryParamsIndex(String url) {

spring-webmvc/src/main/java/org/springframework/web/servlet/resource/TransformedResource.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,11 +20,12 @@ import java.io.IOException;
 
 import org.springframework.core.io.ByteArrayResource;
 import org.springframework.core.io.Resource;
+import org.springframework.lang.Nullable;
 
 /**
- * An extension of {@link org.springframework.core.io.ByteArrayResource}
- * that a {@link ResourceTransformer} can use to represent an original
- * resource preserving all other information except the content.
+ * An extension of {@link ByteArrayResource} that a {@link ResourceTransformer}
+ * can use to represent an original resource preserving all other information
+ * except the content.
  *
  * @author Jeremy Grelle
  * @author Rossen Stoyanchev
@@ -32,6 +33,7 @@ import org.springframework.core.io.Resource;
  */
 public class TransformedResource extends ByteArrayResource {
 
+	@Nullable
 	private final String filename;
 
 	private final long lastModified;

spring-webmvc/src/main/java/org/springframework/web/servlet/support/BindStatus.java

@@ -24,6 +24,7 @@ import org.springframework.beans.BeanWrapper;
 import org.springframework.beans.PropertyAccessorFactory;
 import org.springframework.context.NoSuchMessageException;
 import org.springframework.lang.Nullable;
+import org.springframework.util.ObjectUtils;
 import org.springframework.util.StringUtils;
 import org.springframework.validation.BindingResult;
 import org.springframework.validation.Errors;
@@ -54,24 +55,33 @@ public class BindStatus {
 
 	private final boolean htmlEscape;
 
+	@Nullable
 	private final String expression;
 
+	@Nullable
 	private final Errors errors;
 
+	@Nullable
 	private BindingResult bindingResult;
 
+	@Nullable
 	private Object value;
 
+	@Nullable
 	private Class<?> valueType;
 
+	@Nullable
 	private Object actualValue;
 
+	@Nullable
 	private PropertyEditor editor;
 
+	@Nullable
 	private List<? extends ObjectError> objectErrors;
 
-	private String[] errorCodes;
+	private String[] errorCodes = new String[0];
 
+	@Nullable
 	private String[] errorMessages;
 
 
@@ -133,7 +143,7 @@ public class BindStatus {
 			else {
 				this.objectErrors = this.errors.getGlobalErrors();
 			}
-			initErrorCodes();
+			initErrorCodes(this.objectErrors);
 		}
 
 		else {
@@ -163,27 +173,14 @@ public class BindStatus {
 	/**
 	 * Extract the error codes from the ObjectError list.
 	 */
-	private void initErrorCodes() {
-		this.errorCodes = new String[this.objectErrors.size()];
-		for (int i = 0; i < this.objectErrors.size(); i++) {
-			ObjectError error = this.objectErrors.get(i);
+	private void initErrorCodes(List<? extends ObjectError> objectErrors) {
+		this.errorCodes = new String[objectErrors.size()];
+		for (int i = 0; i < objectErrors.size(); i++) {
+			ObjectError error = objectErrors.get(i);
 			this.errorCodes[i] = error.getCode();
 		}
 	}
 
-	/**
-	 * Extract the error messages from the ObjectError list.
-	 */
-	private void initErrorMessages() throws NoSuchMessageException {
-		if (this.errorMessages == null) {
-			this.errorMessages = new String[this.objectErrors.size()];
-			for (int i = 0; i < this.objectErrors.size(); i++) {
-				ObjectError error = this.objectErrors.get(i);
-				this.errorMessages[i] = this.requestContext.getMessage(error, this.htmlEscape);
-			}
-		}
-	}
-
 
 	/**
 	 * Return the bean and property path for which values and errors
@@ -256,14 +253,13 @@ public class BindStatus {
 	 * Return if this status represents a field or object error.
 	 */
 	public boolean isError() {
-		return (this.errorCodes != null && this.errorCodes.length > 0);
+		return (this.errorCodes.length > 0);
 	}
 
 	/**
 	 * Return the error codes for the field or object, if any.
 	 * Returns an empty array instead of null if none.
 	 */
-	@Nullable
 	public String[] getErrorCodes() {
 		return this.errorCodes;
 	}
@@ -280,16 +276,15 @@ public class BindStatus {
 	 * if any. Returns an empty array instead of null if none.
 	 */
 	public String[] getErrorMessages() {
-		initErrorMessages();
-		return this.errorMessages;
+		return initErrorMessages();
 	}
 
 	/**
 	 * Return the first error message for the field or object, if any.
 	 */
 	public String getErrorMessage() {
-		initErrorMessages();
-		return (this.errorMessages.length > 0 ? this.errorMessages[0] : "");
+		String[] errorMessages = initErrorMessages();
+		return (errorMessages.length > 0 ? errorMessages[0] : "");
 	}
 
 	/**
@@ -299,8 +294,26 @@ public class BindStatus {
 	 * @return the error message string
 	 */
 	public String getErrorMessagesAsString(String delimiter) {
-		initErrorMessages();
-		return StringUtils.arrayToDelimitedString(this.errorMessages, delimiter);
+		return StringUtils.arrayToDelimitedString(initErrorMessages(), delimiter);
+	}
+
+	/**
+	 * Extract the error messages from the ObjectError list.
+	 */
+	private String[] initErrorMessages() throws NoSuchMessageException {
+		if (this.errorMessages == null) {
+			if (this.objectErrors != null) {
+				this.errorMessages = new String[this.objectErrors.size()];
+				for (int i = 0; i < this.objectErrors.size(); i++) {
+					ObjectError error = this.objectErrors.get(i);
+					this.errorMessages[i] = this.requestContext.getMessage(error, this.htmlEscape);
+				}
+			}
+			else {
+				this.errorMessages = new String[0];
+			}
+		}
+		return this.errorMessages;
 	}
 
 	/**
@@ -341,7 +354,7 @@ public class BindStatus {
 		StringBuilder sb = new StringBuilder("BindStatus: ");
 		sb.append("expression=[").append(this.expression).append("]; ");
 		sb.append("value=[").append(this.value).append("]");
-		if (isError()) {
+		if (!ObjectUtils.isEmpty(this.errorCodes)) {
 			sb.append("; errorCodes=").append(Arrays.asList(this.errorCodes));
 		}
 		return sb.toString();

spring-webmvc/src/main/java/org/springframework/web/servlet/support/RequestContext.java

@@ -92,31 +92,43 @@ public class RequestContext {
 	public static final String WEB_APPLICATION_CONTEXT_ATTRIBUTE = RequestContext.class.getName() + ".CONTEXT";
 
 
-	protected static final boolean jstlPresent = ClassUtils.isPresent("javax.servlet.jsp.jstl.core.Config",
-			RequestContext.class.getClassLoader());
+	protected static final boolean jstlPresent = ClassUtils.isPresent(
+			"javax.servlet.jsp.jstl.core.Config", RequestContext.class.getClassLoader());
 
+	@Nullable
 	private HttpServletRequest request;
 
+	@Nullable
 	private HttpServletResponse response;
 
+	@Nullable
 	private Map<String, Object> model;
 
+	@Nullable
 	private WebApplicationContext webApplicationContext;
 
+	@Nullable
 	private Locale locale;
 
+	@Nullable
 	private TimeZone timeZone;
 
+	@Nullable
 	private Theme theme;
 
+	@Nullable
 	private Boolean defaultHtmlEscape;
 
+	@Nullable
 	private Boolean responseEncodedHtmlEscape;
 
+	@Nullable
 	private UrlPathHelper urlPathHelper;
 
+	@Nullable
 	private RequestDataValueProcessor requestDataValueProcessor;
 
+	@Nullable
 	private Map<String, Errors> errorsMap;
 
 
@@ -214,15 +226,15 @@ public class RequestContext {
 	 * @param request current HTTP request
 	 * @param servletContext the servlet context of the web application (can be {@code null}; necessary for
 	 * fallback to root WebApplicationContext)
-	 * @param model the model attributes for the current view (can be {@code null}, using the request attributes
-	 * for Errors retrieval)
+	 * @param model the model attributes for the current view (can be {@code null}, using the request
+	 * attributes for Errors retrieval)
 	 * @see #getFallbackLocale
 	 * @see #getFallbackTheme
 	 * @see org.springframework.web.servlet.DispatcherServlet#LOCALE_RESOLVER_ATTRIBUTE
 	 * @see org.springframework.web.servlet.DispatcherServlet#THEME_RESOLVER_ATTRIBUTE
 	 */
-	protected void initContext(HttpServletRequest request, @Nullable HttpServletResponse response, @Nullable ServletContext servletContext,
-			@Nullable Map<String, Object> model) {
+	protected void initContext(HttpServletRequest request, @Nullable HttpServletResponse response,
+			@Nullable ServletContext servletContext, @Nullable Map<String, Object> model) {
 
 		this.request = request;
 		this.response = response;
@@ -267,7 +279,8 @@ public class RequestContext {
 
 		// Determine response-encoded HTML escape setting from the "responseEncodedHtmlEscape"
 		// context-param in web.xml, if any.
-		this.responseEncodedHtmlEscape = WebUtils.getResponseEncodedHtmlEscape(this.webApplicationContext.getServletContext());
+		this.responseEncodedHtmlEscape =
+				WebUtils.getResponseEncodedHtmlEscape(this.webApplicationContext.getServletContext());
 
 		this.urlPathHelper = new UrlPathHelper();
 
@@ -776,8 +789,8 @@ public class RequestContext {
 	 * @return the message
 	 */
 	public String getThemeMessage(String code, @Nullable List<?> args, String defaultMessage) {
-		return getTheme().getMessageSource().getMessage(code, (args != null ? args.toArray() : null), defaultMessage,
-				this.locale);
+		return getTheme().getMessageSource().getMessage(code, (args != null ? args.toArray() : null),
+				defaultMessage, this.locale);
 	}
 
 	/**

spring-webmvc/src/main/java/org/springframework/web/servlet/support/ServletUriComponentsBuilder.java

@@ -50,6 +50,7 @@ import org.springframework.web.util.UrlPathHelper;
  */
 public class ServletUriComponentsBuilder extends UriComponentsBuilder {
 
+	@Nullable
 	private String originalPath;
 
 

spring-webmvc/src/main/java/org/springframework/web/servlet/support/WebContentGenerator.java

@@ -30,6 +30,7 @@ import javax.servlet.http.HttpServletResponse;
 import org.springframework.http.CacheControl;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpMethod;
+import org.springframework.lang.Nullable;
 import org.springframework.util.ObjectUtils;
 import org.springframework.util.StringUtils;
 import org.springframework.web.HttpRequestMethodNotSupportedException;
@@ -81,16 +82,20 @@ public abstract class WebContentGenerator extends WebApplicationObjectSupport {
 
 
 	/** Set of supported HTTP methods */
+	@Nullable
 	private Set<String> supportedMethods;
 
+	@Nullable
 	private String allowHeader;
 
 	private boolean requireSession = false;
 
+	@Nullable
 	private CacheControl cacheControl;
 
 	private int cacheSeconds = -1;
 
+	@Nullable
 	private String[] varyByRequestHeaders;
 
 
@@ -159,8 +164,9 @@ public abstract class WebContentGenerator extends WebApplicationObjectSupport {
 	/**
 	 * Return the HTTP methods that this content generator supports.
 	 */
+	@Nullable
 	public final String[] getSupportedMethods() {
-		return StringUtils.toStringArray(this.supportedMethods);
+		return (this.supportedMethods != null ? StringUtils.toStringArray(this.supportedMethods) : null);
 	}
 
 	private void initAllowHeader() {
@@ -193,6 +199,7 @@ public abstract class WebContentGenerator extends WebApplicationObjectSupport {
 	 * requests are handled before making a call to
 	 * {@link #checkRequest(HttpServletRequest)}.
 	 */
+	@Nullable
 	protected String getAllowHeader() {
 		return this.allowHeader;
 	}
@@ -225,6 +232,7 @@ public abstract class WebContentGenerator extends WebApplicationObjectSupport {
 	 * that builds the Cache-Control HTTP response header.
 	 * @since 4.2
 	 */
+	@Nullable
 	public final CacheControl getCacheControl() {
 		return this.cacheControl;
 	}
@@ -269,6 +277,7 @@ public abstract class WebContentGenerator extends WebApplicationObjectSupport {
 	 * Return the configured request header names for the "Vary" response header.
 	 * @since 4.3
 	 */
+	@Nullable
 	public final String[] getVaryByRequestHeaders() {
 		return this.varyByRequestHeaders;
 	}
@@ -391,7 +400,7 @@ public abstract class WebContentGenerator extends WebApplicationObjectSupport {
 			applyCacheSeconds(response, this.cacheSeconds);
 		}
 		if (this.varyByRequestHeaders != null) {
-			for (String value : getVaryRequestHeadersToAdd(response)) {
+			for (String value : getVaryRequestHeadersToAdd(response, this.varyByRequestHeaders)) {
 				response.addHeader("Vary", value);
 			}
 		}
@@ -587,18 +596,18 @@ public abstract class WebContentGenerator extends WebApplicationObjectSupport {
 	}
 
 
-	private Collection<String> getVaryRequestHeadersToAdd(HttpServletResponse response) {
+	private Collection<String> getVaryRequestHeadersToAdd(HttpServletResponse response, String[] varyByRequestHeaders) {
 		if (!response.containsHeader(HttpHeaders.VARY)) {
-			return Arrays.asList(getVaryByRequestHeaders());
+			return Arrays.asList(varyByRequestHeaders);
 		}
-		Collection<String> result = new ArrayList<>(getVaryByRequestHeaders().length);
-		Collections.addAll(result, getVaryByRequestHeaders());
+		Collection<String> result = new ArrayList<>(varyByRequestHeaders.length);
+		Collections.addAll(result, varyByRequestHeaders);
 		for (String header : response.getHeaders(HttpHeaders.VARY)) {
 			for (String existing : StringUtils.tokenizeToStringArray(header, ",")) {
 				if ("*".equals(existing)) {
 					return Collections.emptyList();
 				}
-				for (String value : getVaryByRequestHeaders()) {
+				for (String value : varyByRequestHeaders) {
 					if (value.equalsIgnoreCase(existing)) {
 						result.remove(value);
 					}

spring-webmvc/src/main/java/org/springframework/web/servlet/tags/ArgumentTag.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,6 +19,8 @@ package org.springframework.web.servlet.tags;
 import javax.servlet.jsp.JspException;
 import javax.servlet.jsp.tagext.BodyTagSupport;
 
+import org.springframework.lang.Nullable;
+
 /**
  * JSP tag for collecting arguments and passing them to an {@link ArgumentAware}
  * ancestor in the tag hierarchy.
@@ -33,6 +35,7 @@ import javax.servlet.jsp.tagext.BodyTagSupport;
 @SuppressWarnings("serial")
 public class ArgumentTag extends BodyTagSupport {
 
+	@Nullable
 	private Object value;
 
 	private boolean valueSet;

spring-webmvc/src/main/java/org/springframework/web/servlet/tags/BindErrorsTag.java

@@ -20,6 +20,7 @@ import javax.servlet.ServletException;
 import javax.servlet.jsp.JspException;
 import javax.servlet.jsp.PageContext;
 
+import org.springframework.lang.Nullable;
 import org.springframework.validation.Errors;
 
 /**
@@ -38,8 +39,9 @@ public class BindErrorsTag extends HtmlEscapingAwareTag {
 	public static final String ERRORS_VARIABLE_NAME = "errors";
 
 
-	private String name;
+	private String name = "";
 
+	@Nullable
 	private Errors errors;
 
 
@@ -80,6 +82,7 @@ public class BindErrorsTag extends HtmlEscapingAwareTag {
 	 * Retrieve the Errors instance that this tag is currently bound to.
 	 * <p>Intended for cooperating nesting tags.
 	 */
+	@Nullable
 	public final Errors getErrors() {
 		return this.errors;
 	}

spring-webmvc/src/main/java/org/springframework/web/servlet/tags/BindTag.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,11 +17,11 @@
 package org.springframework.web.servlet.tags;
 
 import java.beans.PropertyEditor;
-
 import javax.servlet.jsp.JspTagException;
 import javax.servlet.jsp.PageContext;
 
 import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 import org.springframework.validation.Errors;
 import org.springframework.web.servlet.support.BindStatus;
 
@@ -55,14 +55,17 @@ public class BindTag extends HtmlEscapingAwareTag implements EditorAwareTag {
 	public static final String STATUS_VARIABLE_NAME = "status";
 
 
-	private String path;
+	private String path = "";
 
 	private boolean ignoreNestedPath = false;
 
+	@Nullable
 	private BindStatus status;
 
+	@Nullable
 	private Object previousPageStatus;
 
+	@Nullable
 	private Object previousRequestStatus;
 
 
@@ -150,6 +153,14 @@ public class BindTag extends HtmlEscapingAwareTag implements EditorAwareTag {
 	}
 
 
+	/**
+	 * Return the current BindStatus.
+	 */
+	private BindStatus getStatus() {
+		Assert.state(this.status != null, "No current BindStatus");
+		return this.status;
+	}
+
 	/**
 	 * Retrieve the property that this tag is currently bound to,
 	 * or {@code null} if bound to an object rather than a specific property.
@@ -159,7 +170,7 @@ public class BindTag extends HtmlEscapingAwareTag implements EditorAwareTag {
 	 */
 	@Nullable
 	public final String getProperty() {
-		return this.status.getExpression();
+		return getStatus().getExpression();
 	}
 
 	/**
@@ -169,12 +180,12 @@ public class BindTag extends HtmlEscapingAwareTag implements EditorAwareTag {
 	 */
 	@Nullable
 	public final Errors getErrors() {
-		return this.status.getErrors();
+		return getStatus().getErrors();
 	}
 
 	@Override
 	public final PropertyEditor getEditor() {
-		return this.status.getEditor();
+		return getStatus().getEditor();
 	}
 
 

spring-webmvc/src/main/java/org/springframework/web/servlet/tags/EvalTag.java

@@ -59,8 +59,10 @@ public class EvalTag extends HtmlEscapingAwareTag {
 
 	private final ExpressionParser expressionParser = new SpelExpressionParser();
 
+	@Nullable
 	private Expression expression;
 
+	@Nullable
 	private String var;
 
 	private int scope = PageContext.PAGE_SCOPE;
@@ -114,12 +116,13 @@ public class EvalTag extends HtmlEscapingAwareTag {
 			this.pageContext.setAttribute(EVALUATION_CONTEXT_PAGE_ATTRIBUTE, evaluationContext);
 		}
 		if (this.var != null) {
-			Object result = this.expression.getValue(evaluationContext);
+			Object result = (this.expression != null ? this.expression.getValue(evaluationContext) : null);
 			this.pageContext.setAttribute(this.var, result, this.scope);
 		}
 		else {
 			try {
-				String result = this.expression.getValue(evaluationContext, String.class);
+				String result = (this.expression != null ?
+						this.expression.getValue(evaluationContext, String.class) : null);
 				result = ObjectUtils.getDisplayString(result);
 				result = htmlEscape(result);
 				result = (this.javaScriptEscape ? JavaScriptUtils.javaScriptEscape(result) : result);
@@ -156,6 +159,7 @@ public class EvalTag extends HtmlEscapingAwareTag {
 
 		private final PageContext pageContext;
 
+		@Nullable
 		private final javax.servlet.jsp.el.VariableResolver variableResolver;
 
 		public JspPropertyAccessor(PageContext pageContext) {

spring-webmvc/src/main/java/org/springframework/web/servlet/tags/HtmlEscapingAwareTag.java

@@ -18,6 +18,7 @@ package org.springframework.web.servlet.tags;
 
 import javax.servlet.jsp.JspException;
 
+import org.springframework.lang.Nullable;
 import org.springframework.web.util.HtmlUtils;
 
 /**
@@ -40,6 +41,7 @@ import org.springframework.web.util.HtmlUtils;
 @SuppressWarnings("serial")
 public abstract class HtmlEscapingAwareTag extends RequestContextAwareTag {
 
+	@Nullable
 	private Boolean htmlEscape;
 
 

spring-webmvc/src/main/java/org/springframework/web/servlet/tags/MessageTag.java

@@ -18,6 +18,7 @@ package org.springframework.web.servlet.tags;
 
 import java.io.IOException;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.LinkedList;
 import java.util.List;
 import javax.servlet.jsp.JspException;
@@ -65,18 +66,23 @@ public class MessageTag extends HtmlEscapingAwareTag implements ArgumentAware {
 	public static final String DEFAULT_ARGUMENT_SEPARATOR = ",";
 
 
+	@Nullable
 	private MessageSourceResolvable message;
 
+	@Nullable
 	private String code;
 
+	@Nullable
 	private Object arguments;
 
 	private String argumentSeparator = DEFAULT_ARGUMENT_SEPARATOR;
 
-	private List<Object> nestedArguments;
+	private List<Object> nestedArguments = Collections.emptyList();
 
+	@Nullable
 	private String text;
 
+	@Nullable
 	private String var;
 
 	private String scope = TagUtils.SCOPE_PAGE;

spring-webmvc/src/main/java/org/springframework/web/servlet/tags/NestedPathTag.java

@@ -49,9 +49,11 @@ public class NestedPathTag extends TagSupport implements TryCatchFinally {
 	public static final String NESTED_PATH_VARIABLE_NAME = "nestedPath";
 
 
+	@Nullable
 	private String path;
 
 	/** Caching a previous nested path, so that it may be reset */
+	@Nullable
 	private String previousNestedPath;
 
 
@@ -74,6 +76,7 @@ public class NestedPathTag extends TagSupport implements TryCatchFinally {
 	/**
 	 * Return the path that this tag applies to.
 	 */
+	@Nullable
 	public String getPath() {
 		return this.path;
 	}

spring-webmvc/src/main/java/org/springframework/web/servlet/tags/Param.java

@@ -31,8 +31,10 @@ import org.springframework.lang.Nullable;
  */
 public class Param {
 
+	@Nullable
 	private String name;
 
+	@Nullable
 	private String value;
 
 
@@ -46,6 +48,7 @@ public class Param {
 	/**
 	 * Return the raw parameter name.
 	 */
+	@Nullable
 	public String getName() {
 		return this.name;
 	}
@@ -53,7 +56,7 @@ public class Param {
 	/**
 	 * Set the raw value of the parameter
 	 */
-	public void setValue(String value) {
+	public void setValue(@Nullable String value) {
 		this.value = value;
 	}
 

spring-webmvc/src/main/java/org/springframework/web/servlet/tags/ParamTag.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,6 +19,8 @@ package org.springframework.web.servlet.tags;
 import javax.servlet.jsp.JspException;
 import javax.servlet.jsp.tagext.BodyTagSupport;
 
+import org.springframework.lang.Nullable;
+
 /**
  * JSP tag for collecting name-value parameters and passing them to a
  * {@link ParamAware} ancestor in the tag hierarchy.
@@ -34,8 +36,9 @@ import javax.servlet.jsp.tagext.BodyTagSupport;
 @SuppressWarnings("serial")
 public class ParamTag extends BodyTagSupport {
 
-	private String name;
+	private String name = "";
 
+	@Nullable
 	private String value;
 
 	private boolean valueSet;
@@ -83,7 +86,7 @@ public class ParamTag extends BodyTagSupport {
 	@Override
 	public void release() {
 		super.release();
-		this.name = null;
+		this.name = "";
 		this.value = null;
 		this.valueSet = false;
 	}

spring-webmvc/src/main/java/org/springframework/web/servlet/tags/RequestContextAwareTag.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -24,6 +24,8 @@ import javax.servlet.jsp.tagext.TryCatchFinally;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 
+import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 import org.springframework.web.servlet.support.JspAwareRequestContext;
 import org.springframework.web.servlet.support.RequestContext;
 
@@ -60,6 +62,7 @@ public abstract class RequestContextAwareTag extends TagSupport implements TryCa
 	protected final Log logger = LogFactory.getLog(getClass());
 
 
+	@Nullable
 	private RequestContext requestContext;
 
 
@@ -79,11 +82,7 @@ public abstract class RequestContextAwareTag extends TagSupport implements TryCa
 			}
 			return doStartTagInternal();
 		}
-		catch (JspException ex) {
-			logger.error(ex.getMessage(), ex);
-			throw ex;
-		}
-		catch (RuntimeException ex) {
+		catch (JspException | RuntimeException ex) {
 			logger.error(ex.getMessage(), ex);
 			throw ex;
 		}
@@ -97,6 +96,7 @@ public abstract class RequestContextAwareTag extends TagSupport implements TryCa
 	 * Return the current RequestContext.
 	 */
 	protected final RequestContext getRequestContext() {
+		Assert.state(this.requestContext != null, "No current RequestContext");
 		return this.requestContext;
 	}
 

spring-webmvc/src/main/java/org/springframework/web/servlet/tags/TransformTag.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,6 +21,7 @@ import java.io.IOException;
 import javax.servlet.jsp.JspException;
 import javax.servlet.jsp.tagext.TagSupport;
 
+import org.springframework.lang.Nullable;
 import org.springframework.web.util.TagUtils;
 
 /**
@@ -41,9 +42,11 @@ import org.springframework.web.util.TagUtils;
 public class TransformTag extends HtmlEscapingAwareTag {
 
 	/** the value to transform using the appropriate property editor */
+	@Nullable
 	private Object value;
 
 	/** the variable to put the result in */
+	@Nullable
 	private String var;
 
 	/** the scope of the variable the result will be put in */

spring-webmvc/src/main/java/org/springframework/web/servlet/tags/UrlTag.java

@@ -18,6 +18,7 @@ package org.springframework.web.servlet.tags;
 
 import java.io.IOException;
 import java.io.UnsupportedEncodingException;
+import java.util.Collections;
 import java.util.HashSet;
 import java.util.LinkedList;
 import java.util.List;
@@ -28,6 +29,8 @@ import javax.servlet.http.HttpServletResponse;
 import javax.servlet.jsp.JspException;
 import javax.servlet.jsp.PageContext;
 
+import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
 import org.springframework.web.servlet.support.RequestDataValueProcessor;
 import org.springframework.web.util.JavaScriptUtils;
@@ -82,16 +85,20 @@ public class UrlTag extends HtmlEscapingAwareTag implements ParamAware {
 	private static final String URL_TYPE_ABSOLUTE = "://";
 
 
-	private List<Param> params;
+	private List<Param> params = Collections.emptyList();
 
-	private Set<String> templateParams;
+	private Set<String> templateParams = Collections.emptySet();
 
+	@Nullable
 	private UrlType type;
 
+	@Nullable
 	private String value;
 
+	@Nullable
 	private String context;
 
+	@Nullable
 	private String var;
 
 	private int scope = PageContext.PAGE_SCOPE;
@@ -198,9 +205,11 @@ public class UrlTag extends HtmlEscapingAwareTag implements ParamAware {
 	 * @return the URL value as a String
 	 * @throws JspException
 	 */
-	private String createUrl() throws JspException {
+	String createUrl() throws JspException {
+		Assert.state(this.value != null, "No value set");
 		HttpServletRequest request = (HttpServletRequest) pageContext.getRequest();
 		HttpServletResponse response = (HttpServletResponse) pageContext.getResponse();
+
 		StringBuilder url = new StringBuilder();
 		if (this.type == UrlType.CONTEXT_RELATIVE) {
 			// add application context to url
@@ -231,7 +240,7 @@ public class UrlTag extends HtmlEscapingAwareTag implements ParamAware {
 
 		// HTML and/or JavaScript escape, if demanded.
 		urlStr = htmlEscape(urlStr);
-		urlStr = this.javaScriptEscape ? JavaScriptUtils.javaScriptEscape(urlStr) : urlStr;
+		urlStr = (this.javaScriptEscape ? JavaScriptUtils.javaScriptEscape(urlStr) : urlStr);
 
 		return urlStr;
 	}

spring-webmvc/src/main/java/org/springframework/web/servlet/view/AbstractUrlBasedView.java

@@ -30,6 +30,7 @@ import org.springframework.lang.Nullable;
  */
 public abstract class AbstractUrlBasedView extends AbstractView implements InitializingBean {
 
+	@Nullable
 	private String url;
 
 

spring-webmvc/src/main/java/org/springframework/web/servlet/view/AbstractView.java

@@ -69,10 +69,10 @@ public abstract class AbstractView extends WebApplicationObjectSupport implement
 	private static final int OUTPUT_BYTE_ARRAY_INITIAL_SIZE = 4096;
 
 
-	private String beanName;
-
+	@Nullable
 	private String contentType = DEFAULT_CONTENT_TYPE;
 
+	@Nullable
 	private String requestContextAttribute;
 
 	private final Map<String, Object> staticAttributes = new LinkedHashMap<>();
@@ -81,26 +81,12 @@ public abstract class AbstractView extends WebApplicationObjectSupport implement
 
 	private boolean exposeContextBeansAsAttributes = false;
 
-	private Set<String> exposedContextBeanNames;
-
-
-	/**
-	 * Set the view's name. Helpful for traceability.
-	 * <p>Framework code must call this when constructing views.
-	 */
-	@Override
-	public void setBeanName(String beanName) {
-		this.beanName = beanName;
-	}
-
-	/**
-	 * Return the view's name. Should never be {@code null},
-	 * if the view was correctly configured.
-	 */
 	@Nullable
-	public String getBeanName() {
-		return this.beanName;
-	}
+	private Set<String> exposedContextBeanNames;
+	@Nullable
+	private String beanName;
+
+
 
 	/**
 	 * Set the content type for this view.
@@ -287,6 +273,24 @@ public abstract class AbstractView extends WebApplicationObjectSupport implement
 		this.exposedContextBeanNames = new HashSet<>(Arrays.asList(exposedContextBeanNames));
 	}
 
+	/**
+	 * Set the view's name. Helpful for traceability.
+	 * <p>Framework code must call this when constructing views.
+	 */
+	@Override
+	public void setBeanName(String beanName) {
+		this.beanName = beanName;
+	}
+
+	/**
+	 * Return the view's name. Should never be {@code null},
+	 * if the view was correctly configured.
+	 */
+	@Nullable
+	public String getBeanName() {
+		return this.beanName;
+	}
+
 
 	/**
 	 * Prepares the view given the specified model, merging it with static

spring-webmvc/src/main/java/org/springframework/web/servlet/view/ContentNegotiatingViewResolver.java

@@ -88,27 +88,21 @@ import org.springframework.web.servlet.ViewResolver;
 public class ContentNegotiatingViewResolver extends WebApplicationObjectSupport
 		implements ViewResolver, Ordered, InitializingBean {
 
-	private int order = Ordered.HIGHEST_PRECEDENCE;
-
+	@Nullable
 	private ContentNegotiationManager contentNegotiationManager;
 
 	private final ContentNegotiationManagerFactoryBean cnmFactoryBean = new ContentNegotiationManagerFactoryBean();
 
 	private boolean useNotAcceptableStatusCode = false;
 
+	@Nullable
 	private List<View> defaultViews;
 
+	@Nullable
 	private List<ViewResolver> viewResolvers;
 
+	private int order = Ordered.HIGHEST_PRECEDENCE;
 
-	public void setOrder(int order) {
-		this.order = order;
-	}
-
-	@Override
-	public int getOrder() {
-		return this.order;
-	}
 
 	/**
 	 * Set the {@link ContentNegotiationManager} to use to determine requested media types.
@@ -124,6 +118,7 @@ public class ContentNegotiatingViewResolver extends WebApplicationObjectSupport
 	 * Return the {@link ContentNegotiationManager} to use to determine requested media types.
 	 * @since 4.1.9
 	 */
+	@Nullable
 	public ContentNegotiationManager getContentNegotiationManager() {
 		return this.contentNegotiationManager;
 	}
@@ -157,7 +152,8 @@ public class ContentNegotiatingViewResolver extends WebApplicationObjectSupport
 	}
 
 	public List<View> getDefaultViews() {
-		return Collections.unmodifiableList(this.defaultViews);
+		return (this.defaultViews != null ? Collections.unmodifiableList(this.defaultViews) :
+				Collections.emptyList());
 	}
 
 	/**
@@ -169,7 +165,17 @@ public class ContentNegotiatingViewResolver extends WebApplicationObjectSupport
 	}
 
 	public List<ViewResolver> getViewResolvers() {
-		return Collections.unmodifiableList(this.viewResolvers);
+		return (this.viewResolvers != null ? Collections.unmodifiableList(this.viewResolvers) :
+				Collections.emptyList());
+	}
+
+	public void setOrder(int order) {
+		this.order = order;
+	}
+
+	@Override
+	public int getOrder() {
+		return this.order;
 	}
 
 
@@ -243,6 +249,7 @@ public class ContentNegotiatingViewResolver extends WebApplicationObjectSupport
 	 */
 	@Nullable
 	protected List<MediaType> getMediaTypes(HttpServletRequest request) {
+		Assert.state(this.contentNegotiationManager != null, "No ContentNegotiationManager set");
 		try {
 			ServletWebRequest webRequest = new ServletWebRequest(request);
 
@@ -297,18 +304,21 @@ public class ContentNegotiatingViewResolver extends WebApplicationObjectSupport
 			throws Exception {
 
 		List<View> candidateViews = new ArrayList<>();
-		for (ViewResolver viewResolver : this.viewResolvers) {
-			View view = viewResolver.resolveViewName(viewName, locale);
-			if (view != null) {
-				candidateViews.add(view);
-			}
-			for (MediaType requestedMediaType : requestedMediaTypes) {
-				List<String> extensions = this.contentNegotiationManager.resolveFileExtensions(requestedMediaType);
-				for (String extension : extensions) {
-					String viewNameWithExtension = viewName + '.' + extension;
-					view = viewResolver.resolveViewName(viewNameWithExtension, locale);
-					if (view != null) {
-						candidateViews.add(view);
+		if (this.viewResolvers != null) {
+			Assert.state(this.contentNegotiationManager != null, "No ContentNegotiationManager set");
+			for (ViewResolver viewResolver : this.viewResolvers) {
+				View view = viewResolver.resolveViewName(viewName, locale);
+				if (view != null) {
+					candidateViews.add(view);
+				}
+				for (MediaType requestedMediaType : requestedMediaTypes) {
+					List<String> extensions = this.contentNegotiationManager.resolveFileExtensions(requestedMediaType);
+					for (String extension : extensions) {
+						String viewNameWithExtension = viewName + '.' + extension;
+						view = viewResolver.resolveViewName(viewNameWithExtension, locale);
+						if (view != null) {
+							candidateViews.add(view);
+						}
 					}
 				}
 			}

spring-webmvc/src/main/java/org/springframework/web/servlet/view/InternalResourceViewResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,6 +16,7 @@
 
 package org.springframework.web.servlet.view;
 
+import org.springframework.lang.Nullable;
 import org.springframework.util.ClassUtils;
 
 /**
@@ -50,6 +51,7 @@ public class InternalResourceViewResolver extends UrlBasedViewResolver {
 	private static final boolean jstlPresent = ClassUtils.isPresent(
 			"javax.servlet.jsp.jstl.core.Config", InternalResourceViewResolver.class.getClassLoader());
 
+	@Nullable
 	private Boolean alwaysInclude;
 
 

spring-webmvc/src/main/java/org/springframework/web/servlet/view/JstlView.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,6 +20,7 @@ import javax.servlet.ServletContext;
 import javax.servlet.http.HttpServletRequest;
 
 import org.springframework.context.MessageSource;
+import org.springframework.lang.Nullable;
 import org.springframework.web.servlet.support.JstlUtils;
 import org.springframework.web.servlet.support.RequestContext;
 
@@ -76,6 +77,7 @@ import org.springframework.web.servlet.support.RequestContext;
  */
 public class JstlView extends InternalResourceView {
 
+	@Nullable
 	private MessageSource messageSource;
 
 

spring-webmvc/src/main/java/org/springframework/web/servlet/view/RedirectView.java

@@ -94,14 +94,17 @@ public class RedirectView extends AbstractUrlBasedView implements SmartView {
 
 	private boolean exposeModelAttributes = true;
 
+	@Nullable
 	private String encodingScheme;
 
+	@Nullable
 	private HttpStatus statusCode;
 
 	private boolean expandUriTemplateVariables = true;
 
 	private boolean propagateQueryParams = false;
 
+	@Nullable
 	private String[] hosts;
 
 
@@ -270,6 +273,7 @@ public class RedirectView extends AbstractUrlBasedView implements SmartView {
 	 * Return the configured application hosts.
 	 * @since 4.3
 	 */
+	@Nullable
 	public String[] getHosts() {
 		return this.hosts;
 	}

spring-webmvc/src/main/java/org/springframework/web/servlet/view/ResourceBundleViewResolver.java

@@ -32,6 +32,7 @@ import org.springframework.beans.factory.NoSuchBeanDefinitionException;
 import org.springframework.beans.factory.support.PropertiesBeanDefinitionReader;
 import org.springframework.context.ConfigurableApplicationContext;
 import org.springframework.core.Ordered;
+import org.springframework.lang.Nullable;
 import org.springframework.web.context.support.GenericWebApplicationContext;
 import org.springframework.web.servlet.View;
 
@@ -72,17 +73,17 @@ public class ResourceBundleViewResolver extends AbstractCachingViewResolver
 
 	private ClassLoader bundleClassLoader = Thread.currentThread().getContextClassLoader();
 
+	@Nullable
 	private String defaultParentView;
 
+	@Nullable
 	private Locale[] localesToInitialize;
 
 	/* Locale -> BeanFactory */
-	private final Map<Locale, BeanFactory> localeCache =
-			new HashMap<>();
+	private final Map<Locale, BeanFactory> localeCache = new HashMap<>();
 
 	/* List of ResourceBundle -> BeanFactory */
-	private final Map<List<ResourceBundle>, ConfigurableApplicationContext> bundleCache =
-			new HashMap<>();
+	private final Map<List<ResourceBundle>, ConfigurableApplicationContext> bundleCache = new HashMap<>();
 
 
 	public void setOrder(int order) {

spring-webmvc/src/main/java/org/springframework/web/servlet/view/UrlBasedViewResolver.java

@@ -102,31 +102,39 @@ public class UrlBasedViewResolver extends AbstractCachingViewResolver implements
 	public static final String FORWARD_URL_PREFIX = "forward:";
 
 
+	@Nullable
 	private Class<?> viewClass;
 
 	private String prefix = "";
 
 	private String suffix = "";
 
+	@Nullable
 	private String contentType;
 
 	private boolean redirectContextRelative = true;
 
 	private boolean redirectHttp10Compatible = true;
 
+	@Nullable
 	private String[] redirectHosts;
 
+	@Nullable
 	private String requestContextAttribute;
 
 	/** Map of static attributes, keyed by attribute name (String) */
 	private final Map<String, Object> staticAttributes = new HashMap<>();
 
+	@Nullable
 	private Boolean exposePathVariables;
 
+	@Nullable
 	private Boolean exposeContextBeansAsAttributes;
 
+	@Nullable
 	private String[] exposedContextBeanNames;
 
+	@Nullable
 	private String[] viewNames;
 
 	private int order = Integer.MAX_VALUE;
@@ -276,6 +284,7 @@ public class UrlBasedViewResolver extends AbstractCachingViewResolver implements
 	 * Return the configured application hosts for redirect purposes.
 	 * @since 4.3
 	 */
+	@Nullable
 	public String[] getRedirectHosts() {
 		return this.redirectHosts;
 	}
@@ -467,7 +476,10 @@ public class UrlBasedViewResolver extends AbstractCachingViewResolver implements
 		if (viewName.startsWith(REDIRECT_URL_PREFIX)) {
 			String redirectUrl = viewName.substring(REDIRECT_URL_PREFIX.length());
 			RedirectView view = new RedirectView(redirectUrl, isRedirectContextRelative(), isRedirectHttp10Compatible());
-			view.setHosts(getRedirectHosts());
+			String[] hosts = getRedirectHosts();
+			if (hosts != null) {
+				view.setHosts(hosts);
+			}
 			return applyLifecycleMethods(viewName, view);
 		}
 		// Check for special "forward:" prefix.

spring-webmvc/src/main/java/org/springframework/web/servlet/view/XmlViewResolver.java

@@ -29,6 +29,7 @@ import org.springframework.context.ApplicationContext;
 import org.springframework.context.ConfigurableApplicationContext;
 import org.springframework.core.Ordered;
 import org.springframework.core.io.Resource;
+import org.springframework.lang.Nullable;
 import org.springframework.web.context.support.GenericWebApplicationContext;
 import org.springframework.web.servlet.View;
 
@@ -63,8 +64,10 @@ public class XmlViewResolver extends AbstractCachingViewResolver
 
 	private int order = Integer.MAX_VALUE;  // default: same as non-Ordered
 
+	@Nullable
 	private Resource location;
 
+	@Nullable
 	private ConfigurableApplicationContext cachedFactory;
 
 

spring-webmvc/src/main/java/org/springframework/web/servlet/view/freemarker/FreeMarkerConfig.java

@@ -42,7 +42,7 @@ public interface FreeMarkerConfig {
 	Configuration getConfiguration();
 
 	/**
-	 * Returns the {@link TaglibFactory} used to enable JSP tags to be
+	 * Return the {@link TaglibFactory} used to enable JSP tags to be
 	 * accessed from FreeMarker templates.
 	 */
 	TaglibFactory getTaglibFactory();

spring-webmvc/src/main/java/org/springframework/web/servlet/view/freemarker/FreeMarkerConfigurer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -28,7 +28,9 @@ import freemarker.template.TemplateException;
 
 import org.springframework.beans.factory.InitializingBean;
 import org.springframework.context.ResourceLoaderAware;
+import org.springframework.lang.Nullable;
 import org.springframework.ui.freemarker.FreeMarkerConfigurationFactory;
+import org.springframework.util.Assert;
 import org.springframework.web.context.ServletContextAware;
 
 /**
@@ -78,8 +80,10 @@ import org.springframework.web.context.ServletContextAware;
 public class FreeMarkerConfigurer extends FreeMarkerConfigurationFactory
 		implements FreeMarkerConfig, InitializingBean, ResourceLoaderAware, ServletContextAware {
 
+	@Nullable
 	private Configuration configuration;
 
+	@Nullable
 	private TaglibFactory taglibFactory;
 
 
@@ -133,6 +137,7 @@ public class FreeMarkerConfigurer extends FreeMarkerConfigurationFactory
 	 */
 	@Override
 	public Configuration getConfiguration() {
+		Assert.state(this.configuration != null, "No Configuration available");
 		return this.configuration;
 	}
 
@@ -141,6 +146,7 @@ public class FreeMarkerConfigurer extends FreeMarkerConfigurationFactory
 	 */
 	@Override
 	public TaglibFactory getTaglibFactory() {
+		Assert.state(this.taglibFactory != null, "No TaglibFactory available");
 		return this.taglibFactory;
 	}
 

spring-webmvc/src/main/java/org/springframework/web/servlet/view/freemarker/FreeMarkerView.java

@@ -87,12 +87,16 @@ import org.springframework.web.servlet.view.AbstractTemplateView;
  */
 public class FreeMarkerView extends AbstractTemplateView {
 
+	@Nullable
 	private String encoding;
 
+	@Nullable
 	private Configuration configuration;
 
+	@Nullable
 	private TaglibFactory taglibFactory;
 
+	@Nullable
 	private ServletContextHashModel servletContextHashModel;
 
 

spring-webmvc/src/main/java/org/springframework/web/servlet/view/groovy/GroovyMarkupConfigurer.java

@@ -32,6 +32,7 @@ import org.springframework.context.ApplicationContext;
 import org.springframework.context.ApplicationContextAware;
 import org.springframework.context.i18n.LocaleContextHolder;
 import org.springframework.core.io.Resource;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
 
@@ -87,8 +88,10 @@ public class GroovyMarkupConfigurer extends TemplateConfiguration
 
 	private String resourceLoaderPath = "classpath:";
 
+	@Nullable
 	private MarkupTemplateEngine templateEngine;
 
+	@Nullable
 	private ApplicationContext applicationContext;
 
 
@@ -119,7 +122,8 @@ public class GroovyMarkupConfigurer extends TemplateConfiguration
 	}
 
 	public MarkupTemplateEngine getTemplateEngine() {
-		return templateEngine;
+		Assert.state(this.templateEngine != null, "No MarkupTemplateEngine set");
+		return this.templateEngine;
 	}
 
 	@Override
@@ -128,6 +132,7 @@ public class GroovyMarkupConfigurer extends TemplateConfiguration
 	}
 
 	protected ApplicationContext getApplicationContext() {
+		Assert.state(this.applicationContext != null, "No ApplicationContext set");
 		return this.applicationContext;
 	}
 
@@ -209,6 +214,7 @@ public class GroovyMarkupConfigurer extends TemplateConfiguration
 	 */
 	private class LocaleTemplateResolver implements TemplateResolver {
 
+		@Nullable
 		private ClassLoader classLoader;
 
 		@Override
@@ -218,6 +224,7 @@ public class GroovyMarkupConfigurer extends TemplateConfiguration
 
 		@Override
 		public URL resolveTemplate(String templatePath) throws IOException {
+			Assert.state(this.classLoader != null, "No template ClassLoader available");
 			return GroovyMarkupConfigurer.this.resolveTemplate(this.classLoader, templatePath);
 		}
 	}

spring-webmvc/src/main/java/org/springframework/web/servlet/view/groovy/GroovyMarkupView.java

@@ -31,6 +31,7 @@ import org.springframework.beans.factory.BeanFactoryUtils;
 import org.springframework.beans.factory.NoSuchBeanDefinitionException;
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.ApplicationContextException;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.web.servlet.view.AbstractTemplateView;
 import org.springframework.web.util.NestedServletException;
@@ -50,6 +51,7 @@ import org.springframework.web.util.NestedServletException;
  */
 public class GroovyMarkupView extends AbstractTemplateView {
 
+	@Nullable
 	private MarkupTemplateEngine engine;
 
 
@@ -99,6 +101,7 @@ public class GroovyMarkupView extends AbstractTemplateView {
 
 	@Override
 	public boolean checkResource(Locale locale) throws Exception {
+		Assert.state(this.engine != null, "No MarkupTemplateEngine set");
 		try {
 			this.engine.resolveTemplate(getUrl());
 		}
@@ -124,6 +127,7 @@ public class GroovyMarkupView extends AbstractTemplateView {
 	 * for the given view URL.
 	 */
 	protected Template getTemplate(String viewUrl) throws Exception {
+		Assert.state(this.engine != null, "No MarkupTemplateEngine set");
 		try {
 			return this.engine.createTemplateByPath(viewUrl);
 		}

spring-webmvc/src/main/java/org/springframework/web/servlet/view/json/AbstractJackson2View.java

@@ -31,6 +31,7 @@ import com.fasterxml.jackson.databind.SerializationFeature;
 import com.fasterxml.jackson.databind.ser.FilterProvider;
 
 import org.springframework.http.converter.json.MappingJacksonValue;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.web.servlet.view.AbstractView;
 
@@ -53,6 +54,7 @@ public abstract class AbstractJackson2View extends AbstractView {
 
 	private JsonEncoding encoding = JsonEncoding.UTF8;
 
+	@Nullable
 	private Boolean prettyPrint;
 
 	private boolean disableCaching = true;
@@ -61,7 +63,8 @@ public abstract class AbstractJackson2View extends AbstractView {
 
 
 	protected AbstractJackson2View(ObjectMapper objectMapper, String contentType) {
-		setObjectMapper(objectMapper);
+		this.objectMapper = objectMapper;
+		configurePrettyPrint();
 		setContentType(contentType);
 		setExposePathVariables(false);
 	}
@@ -74,7 +77,6 @@ public abstract class AbstractJackson2View extends AbstractView {
 	 * on the types to be serialized, in which case a custom-configured ObjectMapper is unnecessary.
 	 */
 	public void setObjectMapper(ObjectMapper objectMapper) {
-		Assert.notNull(objectMapper, "'objectMapper' must not be null");
 		this.objectMapper = objectMapper;
 		configurePrettyPrint();
 	}
@@ -184,8 +186,12 @@ public abstract class AbstractJackson2View extends AbstractView {
 		FilterProvider filters = (FilterProvider) model.get(FilterProvider.class.getName());
 		if (serializationView != null || filters != null) {
 			MappingJacksonValue container = new MappingJacksonValue(value);
-			container.setSerializationView(serializationView);
-			container.setFilters(filters);
+			if (serializationView != null) {
+				container.setSerializationView(serializationView);
+			}
+			if (filters != null) {
+				container.setFilters(filters);
+			}
 			value = container;
 		}
 		return value;

spring-webmvc/src/main/java/org/springframework/web/servlet/view/json/MappingJackson2JsonView.java

@@ -78,12 +78,15 @@ public class MappingJackson2JsonView extends AbstractJackson2View {
 	private static final Pattern CALLBACK_PARAM_PATTERN = Pattern.compile("[0-9A-Za-z_\\.]*");
 
 
+	@Nullable
 	private String jsonPrefix;
 
+	@Nullable
 	private Set<String> modelKeys;
 
 	private boolean extractValueFromSingleKeyModel = false;
 
+	@Nullable
 	private Set<String> jsonpParameterNames = new LinkedHashSet<>(Arrays.asList("jsonp", "callback"));
 
 
@@ -146,6 +149,7 @@ public class MappingJackson2JsonView extends AbstractJackson2View {
 	/**
 	 * Return the attributes in the model that should be rendered by this view.
 	 */
+	@Nullable
 	public final Set<String> getModelKeys() {
 		return this.modelKeys;
 	}

spring-webmvc/src/main/java/org/springframework/web/servlet/view/script/ScriptTemplateView.java

@@ -41,7 +41,6 @@ import org.springframework.context.ApplicationContext;
 import org.springframework.context.ApplicationContextException;
 import org.springframework.core.NamedThreadLocal;
 import org.springframework.core.io.Resource;
-import org.springframework.core.io.ResourceLoader;
 import org.springframework.lang.Nullable;
 import org.springframework.scripting.support.StandardScriptEvalException;
 import org.springframework.scripting.support.StandardScriptUtils;
@@ -83,24 +82,31 @@ public class ScriptTemplateView extends AbstractUrlBasedView {
 			new NamedThreadLocal<>("ScriptTemplateView engines");
 
 
+	@Nullable
 	private ScriptEngine engine;
 
+	@Nullable
 	private String engineName;
 
+	@Nullable
 	private Boolean sharedEngine;
 
+	@Nullable
 	private String[] scripts;
 
+	@Nullable
 	private String renderObject;
 
+	@Nullable
 	private String renderFunction;
 
+	@Nullable
 	private Charset charset;
 
+	@Nullable
 	private String[] resourceLoaderPaths;
 
-	private ResourceLoader resourceLoader;
-
+	@Nullable
 	private volatile ScriptEngineManager scriptEngineManager;
 
 
@@ -164,15 +170,6 @@ public class ScriptTemplateView extends AbstractUrlBasedView {
 		this.renderFunction = functionName;
 	}
 
-	/**
-	 * See {@link ScriptTemplateConfigurer#setContentType(String)}} documentation.
-	 * @since 4.2.1
-	 */
-	@Override
-	public void setContentType(@Nullable String contentType) {
-		super.setContentType(contentType);
-	}
-
 	/**
 	 * See {@link ScriptTemplateConfigurer#setCharset(Charset)} documentation.
 	 */
@@ -227,9 +224,6 @@ public class ScriptTemplateView extends AbstractUrlBasedView {
 			String resourceLoaderPath = viewConfig.getResourceLoaderPath();
 			setResourceLoaderPath(resourceLoaderPath == null ? DEFAULT_RESOURCE_LOADER_PATH : resourceLoaderPath);
 		}
-		if (this.resourceLoader == null) {
-			this.resourceLoader = getApplicationContext();
-		}
 		if (this.sharedEngine == null && viewConfig.isSharedEngine() != null) {
 			this.sharedEngine = viewConfig.isSharedEngine();
 		}
@@ -248,11 +242,12 @@ public class ScriptTemplateView extends AbstractUrlBasedView {
 			loadScripts(this.engine);
 		}
 		else {
-			setEngine(createEngineFromName());
+			setEngine(createEngineFromName(this.engineName));
 		}
 
 		if (this.renderFunction != null && this.engine != null) {
-			Assert.isInstanceOf(Invocable.class, this.engine, "ScriptEngine must implement Invocable when 'renderFunction' is specified.");
+			Assert.isInstanceOf(Invocable.class, this.engine,
+					"ScriptEngine must implement Invocable when 'renderFunction' is specified");
 		}
 	}
 
@@ -263,27 +258,31 @@ public class ScriptTemplateView extends AbstractUrlBasedView {
 				engines = new HashMap<>(4);
 				enginesHolder.set(engines);
 			}
+			Assert.state(this.engineName != null, "No engine name specified");
 			Object engineKey = (!ObjectUtils.isEmpty(this.scripts) ?
 					new EngineKey(this.engineName, this.scripts) : this.engineName);
 			ScriptEngine engine = engines.get(engineKey);
 			if (engine == null) {
-				engine = createEngineFromName();
+				engine = createEngineFromName(engineName);
 				engines.put(engineKey, engine);
 			}
 			return engine;
 		}
 		else {
 			// Simply return the configured ScriptEngine...
+			Assert.state(this.engine != null, "No shared engine available");
 			return this.engine;
 		}
 	}
 
-	protected ScriptEngine createEngineFromName() {
-		if (this.scriptEngineManager == null) {
-			this.scriptEngineManager = new ScriptEngineManager(obtainApplicationContext().getClassLoader());
+	protected ScriptEngine createEngineFromName(String engineName) {
+		ScriptEngineManager scriptEngineManager = this.scriptEngineManager;
+		if (scriptEngineManager == null) {
+			scriptEngineManager = new ScriptEngineManager(obtainApplicationContext().getClassLoader());
+			this.scriptEngineManager = scriptEngineManager;
 		}
 
-		ScriptEngine engine = StandardScriptUtils.retrieveEngineByName(this.scriptEngineManager, this.engineName);
+		ScriptEngine engine = StandardScriptUtils.retrieveEngineByName(scriptEngineManager, engineName);
 		loadScripts(engine);
 		return engine;
 	}
@@ -307,10 +306,12 @@ public class ScriptTemplateView extends AbstractUrlBasedView {
 
 	@Nullable
 	protected Resource getResource(String location) {
-		for (String path : this.resourceLoaderPaths) {
-			Resource resource = this.resourceLoader.getResource(path + location);
-			if (resource.exists()) {
-				return resource;
+		if (this.resourceLoaderPaths != null) {
+			for (String path : this.resourceLoaderPaths) {
+				Resource resource = obtainApplicationContext().getResource(path + location);
+				if (resource.exists()) {
+					return resource;
+				}
 			}
 		}
 		return null;
@@ -341,7 +342,9 @@ public class ScriptTemplateView extends AbstractUrlBasedView {
 		super.prepareResponse(request, response);
 
 		setResponseContentType(request, response);
-		response.setCharacterEncoding(this.charset.name());
+		if (this.charset != null) {
+			response.setCharacterEncoding(this.charset.name());
+		}
 	}
 
 	@Override
@@ -375,10 +378,10 @@ public class ScriptTemplateView extends AbstractUrlBasedView {
 			}
 			else if (this.renderObject != null) {
 				Object thiz = engine.eval(this.renderObject);
-				html = ((Invocable)engine).invokeMethod(thiz, this.renderFunction, template, model, context);
+				html = ((Invocable) engine).invokeMethod(thiz, this.renderFunction, template, model, context);
 			}
 			else {
-				html = ((Invocable)engine).invokeFunction(this.renderFunction, template, model, context);
+				html = ((Invocable) engine).invokeFunction(this.renderFunction, template, model, context);
 			}
 
 			response.getWriter().write(String.valueOf(html));
@@ -393,7 +396,9 @@ public class ScriptTemplateView extends AbstractUrlBasedView {
 		if (resource == null) {
 			throw new IllegalStateException("Template resource [" + path + "] not found");
 		}
-		InputStreamReader reader = new InputStreamReader(resource.getInputStream(), this.charset);
+		InputStreamReader reader = (this.charset != null ?
+				new InputStreamReader(resource.getInputStream(), this.charset) :
+				new InputStreamReader(resource.getInputStream()));
 		return FileCopyUtils.copyToString(reader);
 	}
 

spring-webmvc/src/main/java/org/springframework/web/servlet/view/tiles3/TilesConfigurer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -63,6 +63,8 @@ import org.springframework.beans.BeanWrapper;
 import org.springframework.beans.PropertyAccessorFactory;
 import org.springframework.beans.factory.DisposableBean;
 import org.springframework.beans.factory.InitializingBean;
+import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 import org.springframework.web.context.ServletContextAware;
 
@@ -130,20 +132,25 @@ public class TilesConfigurer implements ServletContextAware, InitializingBean, D
 
 	protected final Log logger = LogFactory.getLog(getClass());
 
+	@Nullable
 	private TilesInitializer tilesInitializer;
 
+	@Nullable
 	private String[] definitions;
 
 	private boolean checkRefresh = false;
 
 	private boolean validateDefinitions = true;
 
+	@Nullable
 	private Class<? extends DefinitionsFactory> definitionsFactoryClass;
 
+	@Nullable
 	private Class<? extends PreparerFactory> preparerFactoryClass;
 
 	private boolean useMutableTilesContainer = false;
 
+	@Nullable
 	private ServletContext servletContext;
 
 
@@ -264,6 +271,7 @@ public class TilesConfigurer implements ServletContextAware, InitializingBean, D
 	 */
 	@Override
 	public void afterPropertiesSet() throws TilesException {
+		Assert.state(this.servletContext != null, "No ServletContext available");
 		ApplicationContext preliminaryContext = new SpringWildcardServletTilesApplicationContext(this.servletContext);
 		if (this.tilesInitializer == null) {
 			this.tilesInitializer = new SpringTilesInitializer();
@@ -277,7 +285,9 @@ public class TilesConfigurer implements ServletContextAware, InitializingBean, D
 	 */
 	@Override
 	public void destroy() throws TilesException {
-		this.tilesInitializer.destroy();
+		if (this.tilesInitializer != null) {
+			this.tilesInitializer.destroy();
+		}
 	}
 
 

spring-webmvc/src/main/java/org/springframework/web/servlet/view/tiles3/TilesView.java

@@ -32,6 +32,7 @@ import org.apache.tiles.request.render.Renderer;
 import org.apache.tiles.request.servlet.ServletRequest;
 import org.apache.tiles.request.servlet.ServletUtil;
 
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.web.context.request.RequestAttributes;
 import org.springframework.web.context.request.RequestContextHolder;
@@ -54,12 +55,14 @@ import org.springframework.web.servlet.view.AbstractUrlBasedView;
  */
 public class TilesView extends AbstractUrlBasedView {
 
+	@Nullable
 	private Renderer renderer;
 
 	private boolean exposeJstlAttributes = true;
 
 	private boolean alwaysInclude = false;
 
+	@Nullable
 	private ApplicationContext applicationContext;
 
 
@@ -107,17 +110,21 @@ public class TilesView extends AbstractUrlBasedView {
 
 	@Override
 	public boolean checkResource(final Locale locale) throws Exception {
+		Assert.state(this.renderer != null, "No Renderer set");
+
 		HttpServletRequest servletRequest = null;
 		RequestAttributes requestAttributes = RequestContextHolder.getRequestAttributes();
 		if (requestAttributes instanceof ServletRequestAttributes) {
 			servletRequest = ((ServletRequestAttributes) requestAttributes).getRequest();
 		}
+
 		Request request = new ServletRequest(this.applicationContext, servletRequest, null) {
 			@Override
 			public Locale getRequestLocale() {
 				return locale;
 			}
 		};
+
 		return this.renderer.isRenderable(getUrl(), request);
 	}
 
@@ -125,6 +132,8 @@ public class TilesView extends AbstractUrlBasedView {
 	protected void renderMergedOutputModel(Map<String, Object> model, HttpServletRequest request,
 			HttpServletResponse response) throws Exception {
 
+		Assert.state(this.renderer != null, "No Renderer set");
+
 		exposeModelAsRequestAttributes(model, request);
 		if (this.exposeJstlAttributes) {
 			JstlUtils.exposeLocalizationContext(new RequestContext(request, getServletContext()));

spring-webmvc/src/main/java/org/springframework/web/servlet/view/tiles3/TilesViewResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,6 +18,7 @@ package org.springframework.web.servlet.view.tiles3;
 
 import org.apache.tiles.request.render.Renderer;
 
+import org.springframework.lang.Nullable;
 import org.springframework.web.servlet.view.UrlBasedViewResolver;
 
 /**
@@ -32,8 +33,10 @@ import org.springframework.web.servlet.view.UrlBasedViewResolver;
  */
 public class TilesViewResolver extends UrlBasedViewResolver {
 
+	@Nullable
 	private Renderer renderer;
 
+	@Nullable
 	private Boolean alwaysInclude;
 
 

spring-webmvc/src/main/java/org/springframework/web/servlet/view/xml/MappingJackson2XmlView.java

@@ -22,6 +22,7 @@ import com.fasterxml.jackson.annotation.JsonView;
 import com.fasterxml.jackson.dataformat.xml.XmlMapper;
 
 import org.springframework.http.converter.json.Jackson2ObjectMapperBuilder;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.validation.BindingResult;
 import org.springframework.web.servlet.View;
@@ -47,6 +48,7 @@ public class MappingJackson2XmlView extends AbstractJackson2View {
 	public static final String DEFAULT_CONTENT_TYPE = "application/xml";
 
 
+	@Nullable
 	private String modelKey;
 
 

spring-webmvc/src/main/java/org/springframework/web/servlet/view/xml/MarshallingView.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,7 +18,6 @@ package org.springframework.web.servlet.view.xml;
 
 import java.io.ByteArrayOutputStream;
 import java.util.Map;
-
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import javax.xml.bind.JAXBElement;
@@ -52,8 +51,10 @@ public class MarshallingView extends AbstractView {
 	public static final String DEFAULT_CONTENT_TYPE = "application/xml";
 
 
+	@Nullable
 	private Marshaller marshaller;
 
+	@Nullable
 	private String modelKey;
 
 
@@ -106,6 +107,8 @@ public class MarshallingView extends AbstractView {
 		if (toBeMarshalled == null) {
 			throw new IllegalStateException("Unable to locate object to be marshalled in model: " + model);
 		}
+
+		Assert.state(this.marshaller != null, "No Marshaller set");
 		ByteArrayOutputStream baos = new ByteArrayOutputStream(1024);
 		this.marshaller.marshal(toBeMarshalled, new StreamResult(baos));
 
@@ -159,6 +162,7 @@ public class MarshallingView extends AbstractView {
 	 * @see Marshaller#supports(Class)
 	 */
 	protected boolean isEligibleForMarshalling(String modelKey, Object value) {
+		Assert.state(this.marshaller != null, "No Marshaller set");
 		Class<?> classToCheck = value.getClass();
 		if (value instanceof JAXBElement) {
 			classToCheck = ((JAXBElement) value).getDeclaredType();

spring-webmvc/src/main/java/org/springframework/web/servlet/view/xslt/XsltView.java

@@ -75,22 +75,28 @@ import org.springframework.web.util.WebUtils;
  */
 public class XsltView extends AbstractUrlBasedView {
 
+	@Nullable
 	private Class<? extends TransformerFactory> transformerFactoryClass;
 
+	@Nullable
 	private String sourceKey;
 
+	@Nullable
 	private URIResolver uriResolver;
 
 	private ErrorListener errorListener = new SimpleTransformErrorListener(logger);
 
 	private boolean indent = true;
 
+	@Nullable
 	private Properties outputProperties;
 
 	private boolean cacheTemplates = true;
 
+	@Nullable
 	private TransformerFactory transformerFactory;
 
+	@Nullable
 	private Templates cachedTemplates;
 
 
@@ -215,6 +221,7 @@ public class XsltView extends AbstractUrlBasedView {
 	 * @return the TransformerFactory (never {@code null})
 	 */
 	protected final TransformerFactory getTransformerFactory() {
+		Assert.state(this.transformerFactory != null, "No TransformerFactory available");
 		return this.transformerFactory;
 	}
 
@@ -416,7 +423,7 @@ public class XsltView extends AbstractUrlBasedView {
 	private Templates loadTemplates() throws ApplicationContextException {
 		Source stylesheetSource = getStylesheetSource();
 		try {
-			Templates templates = this.transformerFactory.newTemplates(stylesheetSource);
+			Templates templates = getTransformerFactory().newTemplates(stylesheetSource);
 			if (logger.isDebugEnabled()) {
 				logger.debug("Loading templates '" + templates + "'");
 			}

spring-webmvc/src/main/java/org/springframework/web/servlet/view/xslt/XsltViewResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,6 +20,7 @@ import java.util.Properties;
 import javax.xml.transform.ErrorListener;
 import javax.xml.transform.URIResolver;
 
+import org.springframework.lang.Nullable;
 import org.springframework.web.servlet.view.AbstractUrlBasedView;
 import org.springframework.web.servlet.view.UrlBasedViewResolver;
 
@@ -34,14 +35,18 @@ import org.springframework.web.servlet.view.UrlBasedViewResolver;
  */
 public class XsltViewResolver extends UrlBasedViewResolver {
 
+	@Nullable
 	private String sourceKey;
 
+	@Nullable
 	private URIResolver uriResolver;
 
+	@Nullable
 	private ErrorListener errorListener;
 
 	private boolean indent = true;
 
+	@Nullable
 	private Properties outputProperties;
 
 	private boolean cacheTemplates = true;
@@ -124,7 +129,9 @@ public class XsltViewResolver extends UrlBasedViewResolver {
 	@Override
 	protected AbstractUrlBasedView buildView(String viewName) throws Exception {
 		XsltView view = (XsltView) super.buildView(viewName);
-		view.setSourceKey(this.sourceKey);
+		if (this.sourceKey != null) {
+			view.setSourceKey(this.sourceKey);
+		}
 		if (this.uriResolver != null) {
 			view.setUriResolver(this.uriResolver);
 		}
@@ -132,7 +139,9 @@ public class XsltViewResolver extends UrlBasedViewResolver {
 			view.setErrorListener(this.errorListener);
 		}
 		view.setIndent(this.indent);
-		view.setOutputProperties(this.outputProperties);
+		if (this.outputProperties != null) {
+			view.setOutputProperties(this.outputProperties);
+		}
 		view.setCacheTemplates(this.cacheTemplates);
 		return view;
 	}