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-web/src/main/java/org/springframework/http/HttpHeaders.java

@@ -558,7 +558,7 @@ public class HttpHeaders implements MultiValueMap<String, String>, Serializable
 	/**
 	 * Set the (new) value of the {@code Access-Control-Allow-Origin} response header.
 	 */
-	public void setAccessControlAllowOrigin(String allowedOrigin) {
+	public void setAccessControlAllowOrigin(@Nullable String allowedOrigin) {
 		set(ACCESS_CONTROL_ALLOW_ORIGIN, allowedOrigin);
 	}
 
@@ -617,8 +617,8 @@ public class HttpHeaders implements MultiValueMap<String, String>, Serializable
 	/**
 	 * Set the (new) value of the {@code Access-Control-Request-Method} request header.
 	 */
-	public void setAccessControlRequestMethod(HttpMethod requestMethod) {
-		set(ACCESS_CONTROL_REQUEST_METHOD, requestMethod.name());
+	public void setAccessControlRequestMethod(@Nullable HttpMethod requestMethod) {
+		set(ACCESS_CONTROL_REQUEST_METHOD, (requestMethod != null ? requestMethod.name() : null));
 	}
 
 	/**
@@ -708,7 +708,7 @@ public class HttpHeaders implements MultiValueMap<String, String>, Serializable
 	/**
 	 * Set the (new) value of the {@code Cache-Control} header.
 	 */
-	public void setCacheControl(String cacheControl) {
+	public void setCacheControl(@Nullable String cacheControl) {
 		set(CACHE_CONTROL, cacheControl);
 	}
 
@@ -814,9 +814,8 @@ public class HttpHeaders implements MultiValueMap<String, String>, Serializable
 	 * to set multiple content languages.</p>
 	 * @since 5.0
 	 */
-	public void setContentLanguage(Locale locale) {
-		Assert.notNull(locale, "'locale' must not be null");
-		set(CONTENT_LANGUAGE, locale.toLanguageTag());
+	public void setContentLanguage(@Nullable Locale locale) {
+		set(CONTENT_LANGUAGE, (locale != null ? locale.toLanguageTag() : null));
 	}
 
 	/**
@@ -858,10 +857,15 @@ public class HttpHeaders implements MultiValueMap<String, String>, Serializable
 	 * Set the {@linkplain MediaType media type} of the body,
 	 * as specified by the {@code Content-Type} header.
 	 */
-	public void setContentType(MediaType mediaType) {
-		Assert.isTrue(!mediaType.isWildcardType(), "'Content-Type' cannot contain wildcard type '*'");
-		Assert.isTrue(!mediaType.isWildcardSubtype(), "'Content-Type' cannot contain wildcard subtype '*'");
-		set(CONTENT_TYPE, mediaType.toString());
+	public void setContentType(@Nullable MediaType mediaType) {
+		if (mediaType != null) {
+			Assert.isTrue(!mediaType.isWildcardType(), "'Content-Type' cannot contain wildcard type '*'");
+			Assert.isTrue(!mediaType.isWildcardSubtype(), "'Content-Type' cannot contain wildcard subtype '*'");
+			set(CONTENT_TYPE, mediaType.toString());
+		}
+		else {
+			set(CONTENT_TYPE, null);
+		}
 	}
 
 	/**
@@ -899,10 +903,12 @@ public class HttpHeaders implements MultiValueMap<String, String>, Serializable
 	/**
 	 * Set the (new) entity tag of the body, as specified by the {@code ETag} header.
 	 */
-	public void setETag(String etag) {
-		Assert.isTrue(etag.startsWith("\"") || etag.startsWith("W/"),
-				"Invalid ETag: does not start with W/ or \"");
-		Assert.isTrue(etag.endsWith("\""), "Invalid ETag: does not end with \"");
+	public void setETag(@Nullable String etag) {
+		if (etag != null) {
+			Assert.isTrue(etag.startsWith("\"") || etag.startsWith("W/"),
+					"Invalid ETag: does not start with W/ or \"");
+			Assert.isTrue(etag.endsWith("\""), "Invalid ETag: does not end with \"");
+		}
 		set(ETAG, etag);
 	}
 
@@ -942,10 +948,15 @@ public class HttpHeaders implements MultiValueMap<String, String>, Serializable
 	 * {@linkplain InetSocketAddress#getHostString() hostname}.
 	 * @since 5.0
 	 */
-	public void setHost(InetSocketAddress host) {
-		String value = (host.getPort() != 0 ?
-				String.format("%s:%d", host.getHostString(), host.getPort()) : host.getHostString());
-		set(HOST, value);
+	public void setHost(@Nullable InetSocketAddress host) {
+		if (host != null) {
+			String value = (host.getPort() != 0 ?
+					String.format("%s:%d", host.getHostString(), host.getPort()) : host.getHostString());
+			set(HOST, value);
+		}
+		else {
+			set(HOST, null);
+		}
 	}
 
 	/**
@@ -1089,8 +1100,8 @@ public class HttpHeaders implements MultiValueMap<String, String>, Serializable
 	 * Set the (new) location of a resource,
 	 * as specified by the {@code Location} header.
 	 */
-	public void setLocation(URI location) {
-		set(LOCATION, location.toASCIIString());
+	public void setLocation(@Nullable URI location) {
+		set(LOCATION, (location != null ? location.toASCIIString() : null));
 	}
 
 	/**
@@ -1107,7 +1118,7 @@ public class HttpHeaders implements MultiValueMap<String, String>, Serializable
 	/**
 	 * Set the (new) value of the {@code Origin} header.
 	 */
-	public void setOrigin(String origin) {
+	public void setOrigin(@Nullable String origin) {
 		set(ORIGIN, origin);
 	}
 
@@ -1122,7 +1133,7 @@ public class HttpHeaders implements MultiValueMap<String, String>, Serializable
 	/**
 	 * Set the (new) value of the {@code Pragma} header.
 	 */
-	public void setPragma(String pragma) {
+	public void setPragma(@Nullable String pragma) {
 		set(PRAGMA, pragma);
 	}
 
@@ -1154,7 +1165,7 @@ public class HttpHeaders implements MultiValueMap<String, String>, Serializable
 	/**
 	 * Set the (new) value of the {@code Upgrade} header.
 	 */
-	public void setUpgrade(String upgrade) {
+	public void setUpgrade(@Nullable String upgrade) {
 		set(UPGRADE, upgrade);
 	}
 
@@ -1431,7 +1442,7 @@ public class HttpHeaders implements MultiValueMap<String, String>, Serializable
 	 * @see #add(String, String)
 	 */
 	@Override
-	public void set(String headerName, String headerValue) {
+	public void set(String headerName, @Nullable String headerValue) {
 		List<String> headerValues = new LinkedList<>();
 		headerValues.add(headerValue);
 		this.headers.put(headerName, headerValues);

spring-web/src/main/java/org/springframework/http/codec/AbstractCodecConfigurer.java

@@ -144,7 +144,7 @@ abstract class AbstractCodecConfigurer implements CodecConfigurer {
 		/**
 		 * Access to custom codecs for sub-classes, e.g. for multipart writers.
 		 */
-		public void setCustomCodecs(DefaultCustomCodecs customCodecs) {
+		public void setCustomCodecs(@Nullable DefaultCustomCodecs customCodecs) {
 			this.customCodecs = customCodecs;
 		}
 

spring-web/src/main/java/org/springframework/http/converter/AbstractHttpMessageConverter.java

@@ -110,7 +110,7 @@ public abstract class AbstractHttpMessageConverter<T> implements HttpMessageConv
 	 * Set the default character set, if any.
 	 * @since 4.3
 	 */
-	public void setDefaultCharset(Charset defaultCharset) {
+	public void setDefaultCharset(@Nullable Charset defaultCharset) {
 		this.defaultCharset = defaultCharset;
 	}
 

spring-web/src/main/java/org/springframework/http/converter/BufferedImageHttpMessageConverter.java

@@ -99,12 +99,13 @@ public class BufferedImageHttpMessageConverter implements HttpMessageConverter<B
 	 * Sets the default {@code Content-Type} to be used for writing.
 	 * @throws IllegalArgumentException if the given content type is not supported by the Java Image I/O API
 	 */
-	public void setDefaultContentType(MediaType defaultContentType) {
-		Assert.notNull(defaultContentType, "'contentType' must not be null");
-		Iterator<ImageWriter> imageWriters = ImageIO.getImageWritersByMIMEType(defaultContentType.toString());
-		if (!imageWriters.hasNext()) {
-			throw new IllegalArgumentException(
-					"Content-Type [" + defaultContentType + "] is not supported by the Java Image I/O API");
+	public void setDefaultContentType(@Nullable MediaType defaultContentType) {
+		if (defaultContentType!= null) {
+			Iterator<ImageWriter> imageWriters = ImageIO.getImageWritersByMIMEType(defaultContentType.toString());
+			if (!imageWriters.hasNext()) {
+				throw new IllegalArgumentException(
+						"Content-Type [" + defaultContentType + "] is not supported by the Java Image I/O API");
+			}
 		}
 
 		this.defaultContentType = defaultContentType;

spring-web/src/main/java/org/springframework/http/converter/json/MappingJacksonInputMessage.java

@@ -61,7 +61,7 @@ public class MappingJacksonInputMessage implements HttpInputMessage {
 		return this.headers;
 	}
 
-	public void setDeserializationView(Class<?> deserializationView) {
+	public void setDeserializationView(@Nullable Class<?> deserializationView) {
 		this.deserializationView = deserializationView;
 	}
 

spring-web/src/main/java/org/springframework/http/converter/json/MappingJacksonValue.java

@@ -39,10 +39,13 @@ public class MappingJacksonValue {
 
 	private Object value;
 
+	@Nullable
 	private Class<?> serializationView;
 
+	@Nullable
 	private FilterProvider filters;
 
+	@Nullable
 	private String jsonpFunction;
 
 
@@ -74,7 +77,7 @@ public class MappingJacksonValue {
 	 * @see com.fasterxml.jackson.databind.ObjectMapper#writerWithView(Class)
 	 * @see com.fasterxml.jackson.annotation.JsonView
 	 */
-	public void setSerializationView(Class<?> serializationView) {
+	public void setSerializationView(@Nullable Class<?> serializationView) {
 		this.serializationView = serializationView;
 	}
 
@@ -95,7 +98,7 @@ public class MappingJacksonValue {
 	 * @see com.fasterxml.jackson.annotation.JsonFilter
 	 * @see Jackson2ObjectMapperBuilder#filters(FilterProvider)
 	 */
-	public void setFilters(FilterProvider filters) {
+	public void setFilters(@Nullable FilterProvider filters) {
 		this.filters = filters;
 	}
 
@@ -113,7 +116,7 @@ public class MappingJacksonValue {
 	/**
 	 * Set the name of the JSONP function name.
 	 */
-	public void setJsonpFunction(String functionName) {
+	public void setJsonpFunction(@Nullable String functionName) {
 		this.jsonpFunction = functionName;
 	}
 

spring-web/src/main/java/org/springframework/http/server/reactive/AbstractServerHttpResponse.java

@@ -39,6 +39,7 @@ import org.springframework.util.Assert;
 import org.springframework.util.CollectionUtils;
 import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MultiValueMap;
+import org.springframework.util.StringUtils;
 
 /**
  * Base class for {@link ServerHttpResponse} implementations.
@@ -91,11 +92,10 @@ public abstract class AbstractServerHttpResponse implements ServerHttpResponse {
 	}
 
 	@Override
-	public boolean setStatusCode(HttpStatus statusCode) {
-		Assert.notNull(statusCode, "Status code must not be null");
+	public boolean setStatusCode(@Nullable HttpStatus statusCode) {
 		if (this.state.get() == State.COMMITTED) {
 			if (logger.isDebugEnabled()) {
-				logger.debug("Can't set the status " + statusCode.toString() +
+				logger.debug("Can't set the status " + (statusCode != null ? statusCode.toString() : "null") +
 						" because the HTTP response has already been committed");
 			}
 			return false;

spring-web/src/main/java/org/springframework/http/server/reactive/ServerHttpResponse.java

@@ -39,7 +39,7 @@ public interface ServerHttpResponse extends ReactiveHttpOutputMessage {
 	 * @return {@code false} if the status code has not been set because the HTTP response
 	 * is already committed, {@code true} if it has been set correctly.
 	 */
-	boolean setStatusCode(HttpStatus status);
+	boolean setStatusCode(@Nullable HttpStatus status);
 
 	/**
 	 * Return the HTTP status code or {@code null} if not set.

spring-web/src/main/java/org/springframework/http/server/reactive/ServerHttpResponseDecorator.java

@@ -26,6 +26,7 @@ import org.springframework.core.io.buffer.DataBufferFactory;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.ResponseCookie;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.MultiValueMap;
 
@@ -55,7 +56,7 @@ public class ServerHttpResponseDecorator implements ServerHttpResponse {
 	// ServerHttpResponse delegation methods...
 
 	@Override
-	public boolean setStatusCode(HttpStatus status) {
+	public boolean setStatusCode(@Nullable HttpStatus status) {
 		return getDelegate().setStatusCode(status);
 	}
 

spring-web/src/main/java/org/springframework/remoting/httpinvoker/HttpInvokerClientInterceptor.java

@@ -92,7 +92,7 @@ public class HttpInvokerClientInterceptor extends RemoteInvocationBasedAccessor
 	 * @see org.springframework.remoting.rmi.CodebaseAwareObjectInputStream
 	 * @see java.rmi.server.RMIClassLoader
 	 */
-	public void setCodebaseUrl(String codebaseUrl) {
+	public void setCodebaseUrl(@Nullable String codebaseUrl) {
 		this.codebaseUrl = codebaseUrl;
 	}
 

spring-web/src/main/java/org/springframework/remoting/jaxws/JaxWsPortClientInterceptor.java

@@ -119,7 +119,7 @@ public class JaxWsPortClientInterceptor extends LocalJaxWsServiceFactory
 	 * @see #setServiceName
 	 * @see org.springframework.jndi.JndiObjectFactoryBean
 	 */
-	public void setJaxWsService(Service jaxWsService) {
+	public void setJaxWsService(@Nullable Service jaxWsService) {
 		this.jaxWsService = jaxWsService;
 	}
 
@@ -135,7 +135,7 @@ public class JaxWsPortClientInterceptor extends LocalJaxWsServiceFactory
 	 * Set the name of the port.
 	 * Corresponds to the "wsdl:port" name.
 	 */
-	public void setPortName(String portName) {
+	public void setPortName(@Nullable String portName) {
 		this.portName = portName;
 	}
 
@@ -151,7 +151,7 @@ public class JaxWsPortClientInterceptor extends LocalJaxWsServiceFactory
 	 * Set the username to specify on the stub.
 	 * @see javax.xml.ws.BindingProvider#USERNAME_PROPERTY
 	 */
-	public void setUsername(String username) {
+	public void setUsername(@Nullable String username) {
 		this.username = username;
 	}
 
@@ -167,7 +167,7 @@ public class JaxWsPortClientInterceptor extends LocalJaxWsServiceFactory
 	 * Set the password to specify on the stub.
 	 * @see javax.xml.ws.BindingProvider#PASSWORD_PROPERTY
 	 */
-	public void setPassword(String password) {
+	public void setPassword(@Nullable String password) {
 		this.password = password;
 	}
 
@@ -183,7 +183,7 @@ public class JaxWsPortClientInterceptor extends LocalJaxWsServiceFactory
 	 * Set the endpoint address to specify on the stub.
 	 * @see javax.xml.ws.BindingProvider#ENDPOINT_ADDRESS_PROPERTY
 	 */
-	public void setEndpointAddress(String endpointAddress) {
+	public void setEndpointAddress(@Nullable String endpointAddress) {
 		this.endpointAddress = endpointAddress;
 	}
 
@@ -229,7 +229,7 @@ public class JaxWsPortClientInterceptor extends LocalJaxWsServiceFactory
 	 * Set the SOAP action URI to specify on the stub.
 	 * @see javax.xml.ws.BindingProvider#SOAPACTION_URI_PROPERTY
 	 */
-	public void setSoapActionUri(String soapActionUri) {
+	public void setSoapActionUri(@Nullable String soapActionUri) {
 		this.soapActionUri = soapActionUri;
 	}
 
@@ -289,9 +289,10 @@ public class JaxWsPortClientInterceptor extends LocalJaxWsServiceFactory
 	/**
 	 * Set the interface of the service that this factory should create a proxy for.
 	 */
-	public void setServiceInterface(Class<?> serviceInterface) {
-		Assert.notNull(serviceInterface, "'serviceInterface' must not be null");
-		Assert.isTrue(serviceInterface.isInterface(), "'serviceInterface' must be an interface");
+	public void setServiceInterface(@Nullable Class<?> serviceInterface) {
+		if (serviceInterface != null) {
+			Assert.isTrue(serviceInterface.isInterface(), "'serviceInterface' must be an interface");
+		}
 		this.serviceInterface = serviceInterface;
 	}
 
@@ -318,7 +319,7 @@ public class JaxWsPortClientInterceptor extends LocalJaxWsServiceFactory
 	 * building a client proxy in the {@link JaxWsPortProxyFactoryBean} subclass.
 	 */
 	@Override
-	public void setBeanClassLoader(ClassLoader classLoader) {
+	public void setBeanClassLoader(@Nullable ClassLoader classLoader) {
 		this.beanClassLoader = classLoader;
 	}
 

spring-web/src/main/java/org/springframework/remoting/jaxws/LocalJaxWsServiceFactory.java

@@ -67,7 +67,7 @@ public class LocalJaxWsServiceFactory {
 	 * Set the URL of the WSDL document that describes the service.
 	 * @see #setWsdlDocumentResource(Resource)
 	 */
-	public void setWsdlDocumentUrl(URL wsdlDocumentUrl) {
+	public void setWsdlDocumentUrl(@Nullable URL wsdlDocumentUrl) {
 		this.wsdlDocumentUrl = wsdlDocumentUrl;
 	}
 
@@ -109,7 +109,7 @@ public class LocalJaxWsServiceFactory {
 	 * Set the name of the service to look up.
 	 * Corresponds to the "wsdl:service" name.
 	 */
-	public void setServiceName(String serviceName) {
+	public void setServiceName(@Nullable String serviceName) {
 		this.serviceName = serviceName;
 	}
 

spring-web/src/main/java/org/springframework/web/bind/WebDataBinder.java

@@ -131,7 +131,6 @@ public class WebDataBinder extends DataBinder {
 	/**
 	 * Return the prefix for parameters that mark potentially empty fields.
 	 */
-	@Nullable
 	public String getFieldMarkerPrefix() {
 		return this.fieldMarkerPrefix;
 	}
@@ -157,7 +156,6 @@ public class WebDataBinder extends DataBinder {
 	/**
 	 * Return the prefix for parameters that mark default fields.
 	 */
-	@Nullable
 	public String getFieldDefaultPrefix() {
 		return this.fieldDefaultPrefix;
 	}

spring-web/src/main/java/org/springframework/web/bind/support/ConfigurableWebBindingInitializer.java

@@ -106,7 +106,7 @@ public class ConfigurableWebBindingInitializer implements WebBindingInitializer
 	 * the data binder.
 	 * @see org.springframework.validation.DataBinder#setMessageCodesResolver
 	 */
-	public final void setMessageCodesResolver(MessageCodesResolver messageCodesResolver) {
+	public final void setMessageCodesResolver(@Nullable MessageCodesResolver messageCodesResolver) {
 		this.messageCodesResolver = messageCodesResolver;
 	}
 
@@ -125,7 +125,7 @@ public class ConfigurableWebBindingInitializer implements WebBindingInitializer
 	 * of the data binder.
 	 * @see org.springframework.validation.DataBinder#setBindingErrorProcessor
 	 */
-	public final void setBindingErrorProcessor(BindingErrorProcessor bindingErrorProcessor) {
+	public final void setBindingErrorProcessor(@Nullable BindingErrorProcessor bindingErrorProcessor) {
 		this.bindingErrorProcessor = bindingErrorProcessor;
 	}
 
@@ -140,7 +140,7 @@ public class ConfigurableWebBindingInitializer implements WebBindingInitializer
 	/**
 	 * Set the Validator to apply after each binding step.
 	 */
-	public final void setValidator(Validator validator) {
+	public final void setValidator(@Nullable Validator validator) {
 		this.validator = validator;
 	}
 
@@ -156,7 +156,7 @@ public class ConfigurableWebBindingInitializer implements WebBindingInitializer
 	 * Specify a ConversionService which will apply to every DataBinder.
 	 * @since 3.0
 	 */
-	public final void setConversionService(ConversionService conversionService) {
+	public final void setConversionService(@Nullable ConversionService conversionService) {
 		this.conversionService = conversionService;
 	}
 
@@ -178,7 +178,7 @@ public class ConfigurableWebBindingInitializer implements WebBindingInitializer
 	/**
 	 * Specify multiple PropertyEditorRegistrars to be applied to every DataBinder.
 	 */
-	public final void setPropertyEditorRegistrars(PropertyEditorRegistrar[] propertyEditorRegistrars) {
+	public final void setPropertyEditorRegistrars(@Nullable PropertyEditorRegistrar[] propertyEditorRegistrars) {
 		this.propertyEditorRegistrars = propertyEditorRegistrars;
 	}
 

spring-web/src/main/java/org/springframework/web/context/ConfigurableWebApplicationContext.java

@@ -58,14 +58,14 @@ public interface ConfigurableWebApplicationContext extends WebApplicationContext
 	 * called after the setting of all configuration properties.
 	 * @see #refresh()
 	 */
-	void setServletContext(ServletContext servletContext);
+	void setServletContext(@Nullable ServletContext servletContext);
 
 	/**
 	 * Set the ServletConfig for this web application context.
 	 * Only called for a WebApplicationContext that belongs to a specific Servlet.
 	 * @see #refresh()
 	 */
-	void setServletConfig(ServletConfig servletConfig);
+	void setServletConfig(@Nullable ServletConfig servletConfig);
 
 	/**
 	 * Return the ServletConfig for this web application context, if any.
@@ -78,7 +78,7 @@ public interface ConfigurableWebApplicationContext extends WebApplicationContext
 	 * to be used for building a default context config location.
 	 * The root web application context does not have a namespace.
 	 */
-	void setNamespace(String namespace);
+	void setNamespace(@Nullable String namespace);
 
 	/**
 	 * Return the namespace for this web application context, if any.

spring-web/src/main/java/org/springframework/web/context/support/AbstractRefreshableWebApplicationContext.java

@@ -104,7 +104,7 @@ public abstract class AbstractRefreshableWebApplicationContext extends AbstractR
 
 
 	@Override
-	public void setServletContext(ServletContext servletContext) {
+	public void setServletContext(@Nullable ServletContext servletContext) {
 		this.servletContext = servletContext;
 	}
 
@@ -115,7 +115,7 @@ public abstract class AbstractRefreshableWebApplicationContext extends AbstractR
 	}
 
 	@Override
-	public void setServletConfig(ServletConfig servletConfig) {
+	public void setServletConfig(@Nullable ServletConfig servletConfig) {
 		this.servletConfig = servletConfig;
 		if (this.servletContext == null) {
 			setServletContext(servletConfig.getServletContext());
@@ -129,9 +129,9 @@ public abstract class AbstractRefreshableWebApplicationContext extends AbstractR
 	}
 
 	@Override
-	public void setNamespace(String namespace) {
+	public void setNamespace(@Nullable String namespace) {
 		this.namespace = namespace;
-		setDisplayName("WebApplicationContext for namespace '" + namespace + "'");
+		setDisplayName(namespace != null ? "WebApplicationContext for namespace '" + namespace + "'" : null);
 	}
 
 	@Override

spring-web/src/main/java/org/springframework/web/context/support/AnnotationConfigWebApplicationContext.java

@@ -84,8 +84,10 @@ import org.springframework.web.context.ContextLoader;
 public class AnnotationConfigWebApplicationContext extends AbstractRefreshableWebApplicationContext
 		implements AnnotationConfigRegistry {
 
+	@Nullable
 	private BeanNameGenerator beanNameGenerator;
 
+	@Nullable
 	private ScopeMetadataResolver scopeMetadataResolver;
 
 	private final Set<Class<?>> annotatedClasses = new LinkedHashSet<>();
@@ -100,7 +102,7 @@ public class AnnotationConfigWebApplicationContext extends AbstractRefreshableWe
 	 * @see AnnotatedBeanDefinitionReader#setBeanNameGenerator
 	 * @see ClassPathBeanDefinitionScanner#setBeanNameGenerator
 	 */
-	public void setBeanNameGenerator(BeanNameGenerator beanNameGenerator) {
+	public void setBeanNameGenerator(@Nullable BeanNameGenerator beanNameGenerator) {
 		this.beanNameGenerator = beanNameGenerator;
 	}
 
@@ -120,7 +122,7 @@ public class AnnotationConfigWebApplicationContext extends AbstractRefreshableWe
 	 * @see AnnotatedBeanDefinitionReader#setScopeMetadataResolver
 	 * @see ClassPathBeanDefinitionScanner#setScopeMetadataResolver
 	 */
-	public void setScopeMetadataResolver(ScopeMetadataResolver scopeMetadataResolver) {
+	public void setScopeMetadataResolver(@Nullable ScopeMetadataResolver scopeMetadataResolver) {
 		this.scopeMetadataResolver = scopeMetadataResolver;
 	}
 

spring-web/src/main/java/org/springframework/web/context/support/GenericWebApplicationContext.java

@@ -208,7 +208,7 @@ public class GenericWebApplicationContext extends GenericApplicationContext
 	// ---------------------------------------------------------------------
 
 	@Override
-	public void setServletConfig(ServletConfig servletConfig) {
+	public void setServletConfig(@Nullable ServletConfig servletConfig) {
 		// no-op
 	}
 
@@ -219,7 +219,7 @@ public class GenericWebApplicationContext extends GenericApplicationContext
 	}
 
 	@Override
-	public void setNamespace(String namespace) {
+	public void setNamespace(@Nullable String namespace) {
 		// no-op
 	}
 

spring-web/src/main/java/org/springframework/web/context/support/StaticWebApplicationContext.java

@@ -80,7 +80,7 @@ public class StaticWebApplicationContext extends StaticApplicationContext
 	 * Set the ServletContext that this WebApplicationContext runs in.
 	 */
 	@Override
-	public void setServletContext(ServletContext servletContext) {
+	public void setServletContext(@Nullable ServletContext servletContext) {
 		this.servletContext = servletContext;
 	}
 
@@ -91,7 +91,7 @@ public class StaticWebApplicationContext extends StaticApplicationContext
 	}
 
 	@Override
-	public void setServletConfig(ServletConfig servletConfig) {
+	public void setServletConfig(@Nullable ServletConfig servletConfig) {
 		this.servletConfig = servletConfig;
 		if (this.servletContext == null) {
 			this.servletContext = servletConfig.getServletContext();
@@ -105,9 +105,9 @@ public class StaticWebApplicationContext extends StaticApplicationContext
 	}
 
 	@Override
-	public void setNamespace(String namespace) {
+	public void setNamespace(@Nullable String namespace) {
 		this.namespace = namespace;
-		setDisplayName("WebApplicationContext for namespace '" + namespace + "'");
+		setDisplayName(namespace != null ? "WebApplicationContext for namespace '" + namespace + "'" : null);
 	}
 
 	@Override

spring-web/src/main/java/org/springframework/web/cors/CorsConfiguration.java

@@ -278,7 +278,7 @@ public class CorsConfiguration {
 	 * Whether user credentials are supported.
 	 * <p>By default this is not set (i.e. user credentials are not supported).
 	 */
-	public void setAllowCredentials(Boolean allowCredentials) {
+	public void setAllowCredentials(@Nullable Boolean allowCredentials) {
 		this.allowCredentials = allowCredentials;
 	}
 
@@ -296,7 +296,7 @@ public class CorsConfiguration {
 	 * can be cached by clients.
 	 * <p>By default this is not set.
 	 */
-	public void setMaxAge(Long maxAge) {
+	public void setMaxAge(@Nullable Long maxAge) {
 		this.maxAge = maxAge;
 	}
 

spring-web/src/main/java/org/springframework/web/filter/CharacterEncodingFilter.java

@@ -45,6 +45,7 @@ import org.springframework.util.Assert;
  */
 public class CharacterEncodingFilter extends OncePerRequestFilter {
 
+	@Nullable
 	private String encoding;
 
 	private boolean forceRequestEncoding = false;
@@ -110,7 +111,7 @@ public class CharacterEncodingFilter extends OncePerRequestFilter {
 	 * (and whether it will be applied as default response encoding as well)
 	 * depends on the {@link #setForceEncoding "forceEncoding"} flag.
 	 */
-	public void setEncoding(String encoding) {
+	public void setEncoding(@Nullable String encoding) {
 		this.encoding = encoding;
 	}
 

spring-web/src/main/java/org/springframework/web/filter/DelegatingFilterProxy.java

@@ -174,7 +174,7 @@ public class DelegatingFilterProxy extends GenericFilterBean {
 	 * Set the name of the ServletContext attribute which should be used to retrieve the
 	 * {@link WebApplicationContext} from which to load the delegate {@link Filter} bean.
 	 */
-	public void setContextAttribute(String contextAttribute) {
+	public void setContextAttribute(@Nullable String contextAttribute) {
 		this.contextAttribute = contextAttribute;
 	}
 
@@ -193,7 +193,7 @@ public class DelegatingFilterProxy extends GenericFilterBean {
 	 * <p>By default, the {@code filter-name} as specified for the
 	 * DelegatingFilterProxy in {@code web.xml} will be used.
 	 */
-	public void setTargetBeanName(String targetBeanName) {
+	public void setTargetBeanName(@Nullable String targetBeanName) {
 		this.targetBeanName = targetBeanName;
 	}
 

spring-web/src/main/java/org/springframework/web/jsf/DecoratingNavigationHandler.java

@@ -39,6 +39,7 @@ import org.springframework.lang.Nullable;
  */
 public abstract class DecoratingNavigationHandler extends NavigationHandler {
 
+	@Nullable
 	private NavigationHandler decoratedNavigationHandler;
 
 

spring-web/src/main/java/org/springframework/web/server/i18n/AcceptHeaderLocaleContextResolver.java

@@ -70,7 +70,7 @@ public class AcceptHeaderLocaleContextResolver implements LocaleContextResolver
 	 * have an "Accept-Language" header (not set by default).
 	 * @param defaultLocale the default locale to use
 	 */
-	public void setDefaultLocale(Locale defaultLocale) {
+	public void setDefaultLocale(@Nullable Locale defaultLocale) {
 		this.defaultLocale = defaultLocale;
 	}
 

spring-web/src/main/java/org/springframework/web/util/CookieGenerator.java

@@ -50,12 +50,15 @@ public class CookieGenerator {
 
 	protected final Log logger = LogFactory.getLog(getClass());
 
+	@Nullable
 	private String cookieName;
 
+	@Nullable
 	private String cookieDomain;
 
 	private String cookiePath = DEFAULT_COOKIE_PATH;
 
+	@Nullable 
 	private Integer cookieMaxAge;
 
 	private boolean cookieSecure = false;
@@ -67,13 +70,14 @@ public class CookieGenerator {
 	 * Use the given name for cookies created by this generator.
 	 * @see javax.servlet.http.Cookie#getName()
 	 */
-	public void setCookieName(String cookieName) {
+	public void setCookieName(@Nullable String cookieName) {
 		this.cookieName = cookieName;
 	}
 
 	/**
 	 * Return the given name for cookies created by this generator.
 	 */
+	@Nullable
 	public String getCookieName() {
 		return this.cookieName;
 	}
@@ -83,7 +87,7 @@ public class CookieGenerator {
 	 * The cookie is only visible to servers in this domain.
 	 * @see javax.servlet.http.Cookie#setDomain
 	 */
-	public void setCookieDomain(String cookieDomain) {
+	public void setCookieDomain(@Nullable String cookieDomain) {
 		this.cookieDomain = cookieDomain;
 	}
 
@@ -118,7 +122,7 @@ public class CookieGenerator {
 	 * default.
 	 * @see javax.servlet.http.Cookie#setMaxAge
 	 */
-	public void setCookieMaxAge(Integer cookieMaxAge) {
+	public void setCookieMaxAge(@Nullable Integer cookieMaxAge) {
 		this.cookieMaxAge = cookieMaxAge;
 	}