Make getters and setters null-safety consistent

This commit ensure that null-safety is consistent between
getters and setters in order to be able to provide beans
with properties with a common type when type safety is
taken in account like with Kotlin.

It also add a few missing property level @Nullable
annotations.

Issue: SPR-15792

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

@@ -285,7 +285,7 @@ public abstract class FrameworkServlet extends HttpServletBean implements Applic
 	 * Set the name of the ServletContext attribute which should be used to retrieve the
 	 * {@link WebApplicationContext} that this servlet is supposed to use.
 	 */
-	public void setContextAttribute(String contextAttribute) {
+	public void setContextAttribute(@Nullable String contextAttribute) {
 		this.contextAttribute = contextAttribute;
 	}
 
@@ -322,7 +322,7 @@ public abstract class FrameworkServlet extends HttpServletBean implements Applic
 	 * Specify a custom WebApplicationContext id,
 	 * to be used as serialization id for the underlying BeanFactory.
 	 */
-	public void setContextId(String contextId) {
+	public void setContextId(@Nullable String contextId) {
 		this.contextId = contextId;
 	}
 
@@ -355,7 +355,7 @@ public abstract class FrameworkServlet extends HttpServletBean implements Applic
 	 * location built from the namespace. This location string can consist of
 	 * multiple locations separated by any number of commas and spaces.
 	 */
-	public void setContextConfigLocation(String contextConfigLocation) {
+	public void setContextConfigLocation(@Nullable String contextConfigLocation) {
 		this.contextConfigLocation = contextConfigLocation;
 	}
 

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

@@ -264,7 +264,7 @@ public class ModelAndView {
 	 * <p>The response status is set just prior to View rendering.
 	 * @since 4.3
 	 */
-	public void setStatus(HttpStatus status) {
+	public void setStatus(@Nullable HttpStatus status) {
 		this.status = status;
 	}
 

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

@@ -229,7 +229,7 @@ public class WebMvcConfigurationSupport implements ApplicationContextAware, Serv
 	 * Set the Spring {@link ApplicationContext}, e.g. for resource loading.
 	 */
 	@Override
-	public void setApplicationContext(ApplicationContext applicationContext) {
+	public void setApplicationContext(@Nullable ApplicationContext applicationContext) {
 		this.applicationContext = applicationContext;
 	}
 
@@ -247,7 +247,7 @@ public class WebMvcConfigurationSupport implements ApplicationContextAware, Serv
 	 * looking up file extensions, etc.
 	 */
 	@Override
-	public void setServletContext(ServletContext servletContext) {
+	public void setServletContext(@Nullable ServletContext servletContext) {
 		this.servletContext = servletContext;
 	}
 

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

@@ -104,7 +104,7 @@ public abstract class AbstractHandlerMapping extends WebApplicationObjectSupport
 	 * This handler will be returned if no specific mapping was found.
 	 * <p>Default is {@code null}, indicating no default handler.
 	 */
-	public void setDefaultHandler(Object defaultHandler) {
+	public void setDefaultHandler(@Nullable Object defaultHandler) {
 		this.defaultHandler = defaultHandler;
 	}
 

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

@@ -54,6 +54,7 @@ import org.springframework.web.servlet.HandlerExecutionChain;
  */
 public abstract class AbstractUrlHandlerMapping extends AbstractHandlerMapping implements MatchableHandlerMapping {
 
+	@Nullable
 	private Object rootHandler;
 
 	private boolean useTrailingSlashMatch = false;
@@ -68,7 +69,7 @@ public abstract class AbstractUrlHandlerMapping extends AbstractHandlerMapping i
 	 * the handler to be registered for the root path ("/").
 	 * <p>Default is {@code null}, indicating no root handler.
 	 */
-	public void setRootHandler(Object rootHandler) {
+	public void setRootHandler(@Nullable Object rootHandler) {
 		this.rootHandler = rootHandler;
 	}
 

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

@@ -109,7 +109,7 @@ public final class MappedInterceptor implements HandlerInterceptor {
 	 * PathMatcher implementations that support mapping metadata other than the
 	 * Ant-style path patterns supported by default.
 	 */
-	public void setPathMatcher(PathMatcher pathMatcher) {
+	public void setPathMatcher(@Nullable PathMatcher pathMatcher) {
 		this.pathMatcher = pathMatcher;
 	}
 

spring-webmvc/src/main/java/org/springframework/web/servlet/i18n/AbstractLocaleContextResolver.java

@@ -39,13 +39,14 @@ import org.springframework.web.servlet.LocaleContextResolver;
  */
 public abstract class AbstractLocaleContextResolver extends AbstractLocaleResolver implements LocaleContextResolver {
 
+	@Nullable
 	private TimeZone defaultTimeZone;
 
 
 	/**
 	 * Set a default TimeZone that this resolver will return if no other time zone found.
 	 */
-	public void setDefaultTimeZone(TimeZone defaultTimeZone) {
+	public void setDefaultTimeZone(@Nullable TimeZone defaultTimeZone) {
 		this.defaultTimeZone = defaultTimeZone;
 	}
 

spring-webmvc/src/main/java/org/springframework/web/servlet/i18n/AbstractLocaleResolver.java

@@ -31,13 +31,14 @@ import org.springframework.web.servlet.LocaleResolver;
  */
 public abstract class AbstractLocaleResolver implements LocaleResolver {
 
+	@Nullable
 	private Locale defaultLocale;
 
 
 	/**
 	 * Set a default Locale that this resolver will return if no other locale found.
 	 */
-	public void setDefaultLocale(Locale defaultLocale) {
+	public void setDefaultLocale(@Nullable Locale defaultLocale) {
 		this.defaultLocale = defaultLocale;
 	}
 

spring-webmvc/src/main/java/org/springframework/web/servlet/i18n/AcceptHeaderLocaleResolver.java

@@ -43,6 +43,7 @@ public class AcceptHeaderLocaleResolver implements LocaleResolver {
 
 	private final List<Locale> supportedLocales = new ArrayList<>(4);
 
+	@Nullable
 	private Locale defaultLocale;
 
 
@@ -77,7 +78,7 @@ public class AcceptHeaderLocaleResolver implements LocaleResolver {
 	 * @param defaultLocale the default locale to use
 	 * @since 4.3
 	 */
-	public void setDefaultLocale(Locale defaultLocale) {
+	public void setDefaultLocale(@Nullable Locale defaultLocale) {
 		this.defaultLocale = defaultLocale;
 	}
 

spring-webmvc/src/main/java/org/springframework/web/servlet/i18n/CookieLocaleResolver.java

@@ -127,7 +127,7 @@ public class CookieLocaleResolver extends CookieGenerator implements LocaleConte
 	/**
 	 * Set a fixed Locale that this resolver will return if no cookie found.
 	 */
-	public void setDefaultLocale(Locale defaultLocale) {
+	public void setDefaultLocale(@Nullable Locale defaultLocale) {
 		this.defaultLocale = defaultLocale;
 	}
 
@@ -144,7 +144,7 @@ public class CookieLocaleResolver extends CookieGenerator implements LocaleConte
 	 * Set a fixed TimeZone that this resolver will return if no cookie found.
 	 * @since 4.0
 	 */
-	public void setDefaultTimeZone(TimeZone defaultTimeZone) {
+	public void setDefaultTimeZone(@Nullable TimeZone defaultTimeZone) {
 		this.defaultTimeZone = defaultTimeZone;
 	}
 

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

@@ -38,8 +38,10 @@ import org.springframework.web.servlet.support.RequestContextUtils;
  */
 public class ParameterizableViewController extends AbstractController {
 
+	@Nullable
 	private Object view;
 
+	@Nullable
 	private HttpStatus statusCode;
 
 	private boolean statusOnly;
@@ -55,7 +57,7 @@ public class ParameterizableViewController extends AbstractController {
 	 * DispatcherServlet via a ViewResolver. Will override any pre-existing
 	 * view name or View.
 	 */
-	public void setViewName(String viewName) {
+	public void setViewName(@Nullable String viewName) {
 		this.view = viewName;
 	}
 
@@ -98,7 +100,7 @@ public class ParameterizableViewController extends AbstractController {
 	 * fully handled within the controller.
 	 * @since 4.1
 	 */
-	public void setStatusCode(HttpStatus statusCode) {
+	public void setStatusCode(@Nullable HttpStatus statusCode) {
 		this.statusCode = statusCode;
 	}
 

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

@@ -534,7 +534,7 @@ public final class RequestMappingInfo implements RequestCondition<RequestMapping
 		 * <p>By default this is not set.
 		 * @since 4.2.8
 		 */
-		public void setUrlPathHelper(UrlPathHelper urlPathHelper) {
+		public void setUrlPathHelper(@Nullable UrlPathHelper urlPathHelper) {
 			this.urlPathHelper = urlPathHelper;
 		}
 
@@ -550,7 +550,7 @@ public final class RequestMappingInfo implements RequestCondition<RequestMapping
 		 * Set a custom PathMatcher to use for the PatternsRequestCondition.
 		 * <p>By default this is not set.
 		 */
-		public void setPathMatcher(PathMatcher pathMatcher) {
+		public void setPathMatcher(@Nullable PathMatcher pathMatcher) {
 			this.pathMatcher = pathMatcher;
 		}
 

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

@@ -120,7 +120,7 @@ public class ExceptionHandlerExceptionResolver extends AbstractHandlerMethodExce
 	 * after built-in ones. To override the built-in support for argument
 	 * resolution use {@link #setArgumentResolvers} instead.
 	 */
-	public void setCustomArgumentResolvers(List<HandlerMethodArgumentResolver> argumentResolvers) {
+	public void setCustomArgumentResolvers(@Nullable List<HandlerMethodArgumentResolver> argumentResolvers) {
 		this.customArgumentResolvers= argumentResolvers;
 	}
 
@@ -160,7 +160,7 @@ public class ExceptionHandlerExceptionResolver extends AbstractHandlerMethodExce
 	 * ordered after built-in ones. To override the built-in support for
 	 * return value handling use {@link #setReturnValueHandlers}.
 	 */
-	public void setCustomReturnValueHandlers(List<HandlerMethodReturnValueHandler> returnValueHandlers) {
+	public void setCustomReturnValueHandlers(@Nullable List<HandlerMethodReturnValueHandler> returnValueHandlers) {
 		this.customReturnValueHandlers = returnValueHandlers;
 	}
 
@@ -239,7 +239,7 @@ public class ExceptionHandlerExceptionResolver extends AbstractHandlerMethodExce
 	}
 
 	@Override
-	public void setApplicationContext(ApplicationContext applicationContext) {
+	public void setApplicationContext(@Nullable ApplicationContext applicationContext) {
 		this.applicationContext = applicationContext;
 	}
 

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

@@ -44,6 +44,7 @@ import org.springframework.web.servlet.View;
  */
 public class ModelAndViewMethodReturnValueHandler implements HandlerMethodReturnValueHandler {
 
+	@Nullable
 	private String[] redirectPatterns;
 
 
@@ -56,7 +57,7 @@ public class ModelAndViewMethodReturnValueHandler implements HandlerMethodReturn
 	 * prefix as well.
 	 * @since 4.1
 	 */
-	public void setRedirectPatterns(String... redirectPatterns) {
+	public void setRedirectPatterns(@Nullable String... redirectPatterns) {
 		this.redirectPatterns = redirectPatterns;
 	}
 

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

@@ -196,7 +196,7 @@ public class RequestMappingHandlerAdapter extends AbstractHandlerMethodAdapter
 	 * after built-in ones. To override the built-in support for argument
 	 * resolution use {@link #setArgumentResolvers} instead.
 	 */
-	public void setCustomArgumentResolvers(List<HandlerMethodArgumentResolver> argumentResolvers) {
+	public void setCustomArgumentResolvers(@Nullable List<HandlerMethodArgumentResolver> argumentResolvers) {
 		this.customArgumentResolvers = argumentResolvers;
 	}
 
@@ -258,7 +258,7 @@ public class RequestMappingHandlerAdapter extends AbstractHandlerMethodAdapter
 	 * ordered after built-in ones. To override the built-in support for
 	 * return value handling use {@link #setReturnValueHandlers}.
 	 */
-	public void setCustomReturnValueHandlers(List<HandlerMethodReturnValueHandler> returnValueHandlers) {
+	public void setCustomReturnValueHandlers(@Nullable List<HandlerMethodReturnValueHandler> returnValueHandlers) {
 		this.customReturnValueHandlers = returnValueHandlers;
 	}
 
@@ -307,7 +307,7 @@ public class RequestMappingHandlerAdapter extends AbstractHandlerMethodAdapter
 	 * the return type and controller method information and can be ordered
 	 * freely relative to other return value handlers.
 	 */
-	public void setModelAndViewResolvers(List<ModelAndViewResolver> modelAndViewResolvers) {
+	public void setModelAndViewResolvers(@Nullable List<ModelAndViewResolver> modelAndViewResolvers) {
 		this.modelAndViewResolvers = modelAndViewResolvers;
 	}
 
@@ -369,7 +369,7 @@ public class RequestMappingHandlerAdapter extends AbstractHandlerMethodAdapter
 	 * Provide a WebBindingInitializer with "global" initialization to apply
 	 * to every DataBinder instance.
 	 */
-	public void setWebBindingInitializer(WebBindingInitializer webBindingInitializer) {
+	public void setWebBindingInitializer(@Nullable WebBindingInitializer webBindingInitializer) {
 		this.webBindingInitializer = webBindingInitializer;
 	}
 

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

@@ -44,6 +44,7 @@ import org.springframework.web.servlet.RequestToViewNameTranslator;
  */
 public class ViewNameMethodReturnValueHandler implements HandlerMethodReturnValueHandler {
 
+	@Nullable
 	private String[] redirectPatterns;
 
 
@@ -56,7 +57,7 @@ public class ViewNameMethodReturnValueHandler implements HandlerMethodReturnValu
 	 * prefix as well.
 	 * @since 4.1
 	 */
-	public void setRedirectPatterns(String... redirectPatterns) {
+	public void setRedirectPatterns(@Nullable String... redirectPatterns) {
 		this.redirectPatterns = redirectPatterns;
 	}
 

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

@@ -43,6 +43,7 @@ import org.springframework.web.context.support.ServletContextResource;
  */
 public class PathResourceResolver extends AbstractResourceResolver {
 
+	@Nullable
 	private Resource[] allowedLocations;
 
 
@@ -63,7 +64,7 @@ public class PathResourceResolver extends AbstractResourceResolver {
 	 * @since 4.1.2
 	 * @see ResourceHttpRequestHandler#initAllowedLocations()
 	 */
-	public void setAllowedLocations(Resource... locations) {
+	public void setAllowedLocations(@Nullable Resource... locations) {
 		this.allowedLocations = locations;
 	}
 

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

@@ -181,7 +181,7 @@ public class ResourceHttpRequestHandler extends WebContentGenerator
 	 * <p>By default a {@link ResourceHttpMessageConverter} will be configured.
 	 * @since 4.3
 	 */
-	public void setResourceHttpMessageConverter(ResourceHttpMessageConverter messageConverter) {
+	public void setResourceHttpMessageConverter(@Nullable ResourceHttpMessageConverter messageConverter) {
 		this.resourceHttpMessageConverter = messageConverter;
 	}
 
@@ -199,7 +199,7 @@ public class ResourceHttpRequestHandler extends WebContentGenerator
 	 * <p>By default a {@link ResourceRegionHttpMessageConverter} will be configured.
 	 * @since 4.3
 	 */
-	public void setResourceRegionHttpMessageConverter(ResourceRegionHttpMessageConverter messageConverter) {
+	public void setResourceRegionHttpMessageConverter(@Nullable ResourceRegionHttpMessageConverter messageConverter) {
 		this.resourceRegionHttpMessageConverter = messageConverter;
 	}
 
@@ -219,7 +219,7 @@ public class ResourceHttpRequestHandler extends WebContentGenerator
 	 * @param contentNegotiationManager the manager in use
 	 * @since 4.3
 	 */
-	public void setContentNegotiationManager(ContentNegotiationManager contentNegotiationManager) {
+	public void setContentNegotiationManager(@Nullable ContentNegotiationManager contentNegotiationManager) {
 		this.contentNegotiationManager = contentNegotiationManager;
 	}
 

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

@@ -45,7 +45,7 @@ public abstract class ResourceTransformerSupport implements ResourceTransformer
 	 * This is required only for links expressed as full paths and not for
 	 * relative links.
 	 */
-	public void setResourceUrlProvider(ResourceUrlProvider resourceUrlProvider) {
+	public void setResourceUrlProvider(@Nullable ResourceUrlProvider resourceUrlProvider) {
 		this.resourceUrlProvider = resourceUrlProvider;
 	}
 

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

@@ -151,7 +151,7 @@ public abstract class WebContentGenerator extends WebApplicationObjectSupport {
 	 * <p>Default is GET, HEAD and POST for simple form controller types;
 	 * unrestricted for general controllers and interceptors.
 	 */
-	public final void setSupportedMethods(String... methods) {
+	public final void setSupportedMethods(@Nullable String... methods) {
 		if (!ObjectUtils.isEmpty(methods)) {
 			this.supportedMethods = new LinkedHashSet<>(Arrays.asList(methods));
 		}
@@ -223,7 +223,7 @@ public abstract class WebContentGenerator extends WebApplicationObjectSupport {
 	 * the Cache-Control HTTP response header.
 	 * @since 4.2
 	 */
-	public final void setCacheControl(CacheControl cacheControl) {
+	public final void setCacheControl(@Nullable CacheControl cacheControl) {
 		this.cacheControl = cacheControl;
 	}
 
@@ -269,7 +269,7 @@ public abstract class WebContentGenerator extends WebApplicationObjectSupport {
 	 * @param varyByRequestHeaders one or more request header names
 	 * @since 4.3
 	 */
-	public final void setVaryByRequestHeaders(String... varyByRequestHeaders) {
+	public final void setVaryByRequestHeaders(@Nullable String... varyByRequestHeaders) {
 		this.varyByRequestHeaders = varyByRequestHeaders;
 	}
 

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

@@ -41,7 +41,7 @@ public class Param {
 	/**
 	 * Set the raw name of the parameter
 	 */
-	public void setName(String name) {
+	public void setName(@Nullable String name) {
 		this.name = name;
 	}
 

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

@@ -53,7 +53,7 @@ public abstract class AbstractUrlBasedView extends AbstractView implements Initi
 	 * Set the URL of the resource that this view wraps.
 	 * The URL must be appropriate for the concrete View implementation.
 	 */
-	public void setUrl(String url) {
+	public void setUrl(@Nullable String url) {
 		this.url = url;
 	}
 

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

@@ -83,6 +83,7 @@ public abstract class AbstractView extends WebApplicationObjectSupport implement
 
 	@Nullable
 	private Set<String> exposedContextBeanNames;
+	
 	@Nullable
 	private String beanName;
 
@@ -278,7 +279,7 @@ public abstract class AbstractView extends WebApplicationObjectSupport implement
 	 * <p>Framework code must call this when constructing views.
 	 */
 	@Override
-	public void setBeanName(String beanName) {
+	public void setBeanName(@Nullable String beanName) {
 		this.beanName = beanName;
 	}
 

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

@@ -110,7 +110,7 @@ public class ContentNegotiatingViewResolver extends WebApplicationObjectSupport
 	 * applying a {@link org.springframework.web.accept.HeaderContentNegotiationStrategy}.
 	 * @see ContentNegotiationManager#ContentNegotiationManager()
 	 */
-	public void setContentNegotiationManager(ContentNegotiationManager contentNegotiationManager) {
+	public void setContentNegotiationManager(@Nullable ContentNegotiationManager contentNegotiationManager) {
 		this.contentNegotiationManager = contentNegotiationManager;
 	}
 

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

@@ -265,7 +265,7 @@ public class RedirectView extends AbstractUrlBasedView implements SmartView {
 	 * @param hosts one or more application hosts
 	 * @since 4.3
 	 */
-	public void setHosts(String... hosts) {
+	public void setHosts(@Nullable String... hosts) {
 		this.hosts = hosts;
 	}
 

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

@@ -146,8 +146,8 @@ public class UrlBasedViewResolver extends AbstractCachingViewResolver implements
 	 * (by default, AbstractUrlBasedView)
 	 * @see AbstractUrlBasedView
 	 */
-	public void setViewClass(Class<?> viewClass) {
-		if (!requiredViewClass().isAssignableFrom(viewClass)) {
+	public void setViewClass(@Nullable Class<?> viewClass) {
+		if (viewClass != null && !requiredViewClass().isAssignableFrom(viewClass)) {
 			throw new IllegalArgumentException("Given view class [" + viewClass.getName() +
 					"] is not of type [" + requiredViewClass().getName() + "]");
 		}
@@ -204,7 +204,7 @@ public class UrlBasedViewResolver extends AbstractCachingViewResolver implements
 	 * <p>May be ignored by view classes if the view itself is assumed
 	 * to set the content type, e.g. in case of JSPs.
 	 */
-	public void setContentType(String contentType) {
+	public void setContentType(@Nullable String contentType) {
 		this.contentType = contentType;
 	}
 
@@ -276,7 +276,7 @@ public class UrlBasedViewResolver extends AbstractCachingViewResolver implements
 	 * @param redirectHosts one or more application hosts
 	 * @since 4.3
 	 */
-	public void setRedirectHosts(String... redirectHosts) {
+	public void setRedirectHosts(@Nullable String... redirectHosts) {
 		this.redirectHosts = redirectHosts;
 	}
 
@@ -294,7 +294,7 @@ public class UrlBasedViewResolver extends AbstractCachingViewResolver implements
 	 * @param requestContextAttribute name of the RequestContext attribute
 	 * @see AbstractView#setRequestContextAttribute
 	 */
-	public void setRequestContextAttribute(String requestContextAttribute) {
+	public void setRequestContextAttribute(@Nullable String requestContextAttribute) {
 		this.requestContextAttribute = requestContextAttribute;
 	}
 
@@ -393,7 +393,7 @@ public class UrlBasedViewResolver extends AbstractCachingViewResolver implements
 	 * attributes.
 	 * @see AbstractView#setExposedContextBeanNames
 	 */
-	public void setExposedContextBeanNames(String... exposedContextBeanNames) {
+	public void setExposedContextBeanNames(@Nullable String... exposedContextBeanNames) {
 		this.exposedContextBeanNames = exposedContextBeanNames;
 	}
 
@@ -409,7 +409,7 @@ public class UrlBasedViewResolver extends AbstractCachingViewResolver implements
 	 * view name 'myReport'.
 	 * @see #canHandle
 	 */
-	public void setViewNames(String... viewNames) {
+	public void setViewNames(@Nullable String... viewNames) {
 		this.viewNames = viewNames;
 	}
 

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

@@ -106,7 +106,7 @@ public class FreeMarkerView extends AbstractTemplateView {
 	 * <p>Specify the encoding in the FreeMarker Configuration rather than per
 	 * template if all your templates share a common encoding.
 	 */
-	public void setEncoding(String encoding) {
+	public void setEncoding(@Nullable String encoding) {
 		this.encoding = encoding;
 	}
 
@@ -127,7 +127,7 @@ public class FreeMarkerView extends AbstractTemplateView {
 	 * in terms of memory and initial CPU usage. In production it is recommended that you use
 	 * a {@link FreeMarkerConfig} which exposes a single shared {@link TaglibFactory}.
 	 */
-	public void setConfiguration(Configuration configuration) {
+	public void setConfiguration(@Nullable Configuration configuration) {
 		this.configuration = configuration;
 	}
 

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

@@ -142,7 +142,7 @@ public class MappingJackson2JsonView extends AbstractJackson2View {
 	 * Set the attributes in the model that should be rendered by this view.
 	 * When set, all other model attributes will be ignored.
 	 */
-	public void setModelKeys(Set<String> modelKeys) {
+	public void setModelKeys(@Nullable Set<String> modelKeys) {
 		this.modelKeys = modelKeys;
 	}