Add nullability annotations to module/spring-boot-webflux

See gh-46587

module/spring-boot-webflux/src/main/java/org/springframework/boot/webflux/actuate/endpoint/web/AbstractWebFluxEndpointHandlerMapping.java

@@ -26,6 +26,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.function.Supplier;
 
+import org.jspecify.annotations.Nullable;
 import org.reactivestreams.Publisher;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
@@ -56,11 +57,13 @@ import org.springframework.http.HttpMethod;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.MediaType;
 import org.springframework.http.ResponseEntity;
+import org.springframework.http.ResponseEntity.BodyBuilder;
 import org.springframework.security.authorization.AuthorityAuthorizationManager;
 import org.springframework.security.authorization.AuthorizationResult;
 import org.springframework.security.core.Authentication;
 import org.springframework.security.core.context.ReactiveSecurityContextHolder;
 import org.springframework.util.AntPathMatcher;
+import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.ReflectionUtils;
 import org.springframework.util.StringUtils;
@@ -96,13 +99,11 @@ public abstract class AbstractWebFluxEndpointHandlerMapping extends RequestMappi
 
 	private final EndpointMediaTypes endpointMediaTypes;
 
-	private final CorsConfiguration corsConfiguration;
+	private final @Nullable CorsConfiguration corsConfiguration;
 
-	private final Method handleWriteMethod = ReflectionUtils.findMethod(WriteOperationHandler.class, "handle",
-			ServerWebExchange.class, Map.class);
+	private final Method handleWriteMethod = getHandleWriteMethod();
 
-	private final Method handleReadMethod = ReflectionUtils.findMethod(ReadOperationHandler.class, "handle",
-			ServerWebExchange.class);
+	private final Method handleReadMethod = getHandleReadMethod();
 
 	private final boolean shouldRegisterLinksMapping;
 
@@ -117,7 +118,7 @@ public abstract class AbstractWebFluxEndpointHandlerMapping extends RequestMappi
 	 */
 	public AbstractWebFluxEndpointHandlerMapping(EndpointMapping endpointMapping,
 			Collection<ExposableWebEndpoint> endpoints, EndpointMediaTypes endpointMediaTypes,
-			CorsConfiguration corsConfiguration, boolean shouldRegisterLinksMapping) {
+			@Nullable CorsConfiguration corsConfiguration, boolean shouldRegisterLinksMapping) {
 		this.endpointMapping = endpointMapping;
 		this.endpoints = endpoints;
 		this.endpointMediaTypes = endpointMediaTypes;
@@ -126,6 +127,19 @@ public abstract class AbstractWebFluxEndpointHandlerMapping extends RequestMappi
 		setOrder(-100);
 	}
 
+	private static Method getHandleWriteMethod() {
+		Method method = ReflectionUtils.findMethod(WriteOperationHandler.class, "handle", ServerWebExchange.class,
+				Map.class);
+		Assert.state(method != null, "'method' must not be null");
+		return method;
+	}
+
+	private static Method getHandleReadMethod() {
+		Method method = ReflectionUtils.findMethod(ReadOperationHandler.class, "handle", ServerWebExchange.class);
+		Assert.state(method != null, "'method' must not be null");
+		return method;
+	}
+
 	@Override
 	protected void initHandlerMethods() {
 		for (ExposableWebEndpoint endpoint : this.endpoints) {
@@ -204,8 +218,9 @@ public abstract class AbstractWebFluxEndpointHandlerMapping extends RequestMappi
 			.produces(produces)
 			.build();
 		LinksHandler linksHandler = getLinksHandler();
-		registerMapping(mapping, linksHandler,
-				ReflectionUtils.findMethod(linksHandler.getClass(), "links", ServerWebExchange.class));
+		Method linksMethod = ReflectionUtils.findMethod(linksHandler.getClass(), "links", ServerWebExchange.class);
+		Assert.state(linksMethod != null, "'linksMethod' must not be null");
+		registerMapping(mapping, linksHandler, linksMethod);
 	}
 
 	@Override
@@ -214,12 +229,13 @@ public abstract class AbstractWebFluxEndpointHandlerMapping extends RequestMappi
 	}
 
 	@Override
-	protected CorsConfiguration initCorsConfiguration(Object handler, Method method, RequestMappingInfo mapping) {
+	protected @Nullable CorsConfiguration initCorsConfiguration(Object handler, Method method,
+			RequestMappingInfo mapping) {
 		return this.corsConfiguration;
 	}
 
 	@Override
-	protected CorsConfiguration getCorsConfiguration(Object handler, ServerWebExchange exchange) {
+	protected @Nullable CorsConfiguration getCorsConfiguration(Object handler, ServerWebExchange exchange) {
 		CorsConfiguration corsConfiguration = super.getCorsConfiguration(handler, exchange);
 		return (corsConfiguration != null) ? corsConfiguration : this.corsConfiguration;
 	}
@@ -230,7 +246,7 @@ public abstract class AbstractWebFluxEndpointHandlerMapping extends RequestMappi
 	}
 
 	@Override
-	protected RequestMappingInfo getMappingForMethod(Method method, Class<?> handlerType) {
+	protected @Nullable RequestMappingInfo getMappingForMethod(Method method, Class<?> handlerType) {
 		return null;
 	}
 
@@ -277,7 +293,7 @@ public abstract class AbstractWebFluxEndpointHandlerMapping extends RequestMappi
 		}
 
 		@Override
-		public Object invoke(InvocationContext context) {
+		public @Nullable Object invoke(InvocationContext context) {
 			try {
 				return this.invoker.invoke(context);
 			}
@@ -304,7 +320,7 @@ public abstract class AbstractWebFluxEndpointHandlerMapping extends RequestMappi
 	@FunctionalInterface
 	protected interface ReactiveWebOperation {
 
-		Mono<ResponseEntity<Object>> handle(ServerWebExchange exchange, Map<String, String> body);
+		Mono<ResponseEntity<Object>> handle(ServerWebExchange exchange, @Nullable Map<String, String> body);
 
 	}
 
@@ -355,7 +371,7 @@ public abstract class AbstractWebFluxEndpointHandlerMapping extends RequestMappi
 		}
 
 		@Override
-		public Mono<ResponseEntity<Object>> handle(ServerWebExchange exchange, Map<String, String> body) {
+		public Mono<ResponseEntity<Object>> handle(ServerWebExchange exchange, @Nullable Map<String, String> body) {
 			Map<String, Object> arguments = getArguments(exchange, body);
 			OperationArgumentResolver serverNamespaceArgumentResolver = OperationArgumentResolver
 				.of(WebServerNamespace.class, () -> WebServerNamespace
@@ -369,7 +385,7 @@ public abstract class AbstractWebFluxEndpointHandlerMapping extends RequestMappi
 						exchange.getRequest().getMethod()));
 		}
 
-		private Map<String, Object> getArguments(ServerWebExchange exchange, Map<String, String> body) {
+		private Map<String, Object> getArguments(ServerWebExchange exchange, @Nullable Map<String, String> body) {
 			Map<String, Object> arguments = new LinkedHashMap<>(getTemplateVariables(exchange));
 			String matchAllRemainingPathSegmentsVariable = this.operation.getRequestPredicate()
 				.getMatchAllRemainingPathSegmentsVariable();
@@ -387,6 +403,7 @@ public abstract class AbstractWebFluxEndpointHandlerMapping extends RequestMappi
 
 		private Object getRemainingPathSegments(ServerWebExchange exchange) {
 			PathPattern pathPattern = exchange.getAttribute(HandlerMapping.BEST_MATCHING_PATTERN_ATTRIBUTE);
+			Assert.state(pathPattern != null, "'pathPattern' must not be null");
 			if (pathPattern.hasPatternSyntax()) {
 				String remainingSegments = pathPattern
 					.extractPathWithinPattern(exchange.getRequest().getPath().pathWithinApplication())
@@ -407,10 +424,12 @@ public abstract class AbstractWebFluxEndpointHandlerMapping extends RequestMappi
 		}
 
 		private Map<String, String> getTemplateVariables(ServerWebExchange exchange) {
-			return exchange.getAttribute(HandlerMapping.URI_TEMPLATE_VARIABLES_ATTRIBUTE);
+			Map<String, String> result = exchange.getAttribute(HandlerMapping.URI_TEMPLATE_VARIABLES_ATTRIBUTE);
+			Assert.state(result != null, "'result' must not be null");
+			return result;
 		}
 
-		private Mono<ResponseEntity<Object>> handleResult(Publisher<?> result, HttpMethod httpMethod) {
+		private Mono<ResponseEntity<Object>> handleResult(@Nullable Publisher<?> result, HttpMethod httpMethod) {
 			if (result instanceof Flux) {
 				result = ((Flux<?>) result).collectList();
 			}
@@ -428,9 +447,11 @@ public abstract class AbstractWebFluxEndpointHandlerMapping extends RequestMappi
 			}
 			MediaType contentType = (webEndpointResponse.getContentType() != null)
 					? new MediaType(webEndpointResponse.getContentType()) : null;
-			return ResponseEntity.status(webEndpointResponse.getStatus())
-				.contentType(contentType)
-				.body(webEndpointResponse.getBody());
+			BodyBuilder builder = ResponseEntity.status(webEndpointResponse.getStatus());
+			if (contentType != null) {
+				builder = builder.contentType(contentType);
+			}
+			return builder.body(webEndpointResponse.getBody());
 		}
 
 		@Override
@@ -512,18 +533,18 @@ public abstract class AbstractWebFluxEndpointHandlerMapping extends RequestMappi
 
 		private static final String ROLE_PREFIX = "ROLE_";
 
-		private final Authentication authentication;
+		private final @Nullable Authentication authentication;
 
-		ReactiveSecurityContext(Authentication authentication) {
+		ReactiveSecurityContext(@Nullable Authentication authentication) {
 			this.authentication = authentication;
 		}
 
-		private Authentication getAuthentication() {
+		private @Nullable Authentication getAuthentication() {
 			return this.authentication;
 		}
 
 		@Override
-		public Principal getPrincipal() {
+		public @Nullable Principal getPrincipal() {
 			return this.authentication;
 		}
 
@@ -531,7 +552,7 @@ public abstract class AbstractWebFluxEndpointHandlerMapping extends RequestMappi
 		public boolean isUserInRole(String role) {
 			String authority = (!role.startsWith(ROLE_PREFIX)) ? ROLE_PREFIX + role : role;
 			AuthorizationResult result = AuthorityAuthorizationManager.hasAuthority(authority)
-				.authorize(this::getAuthentication, null);
+				.authorize(this::getAuthentication, new Object());
 			return result != null && result.isGranted();
 		}
 
@@ -542,7 +563,7 @@ public abstract class AbstractWebFluxEndpointHandlerMapping extends RequestMappi
 		private final ReflectiveRuntimeHintsRegistrar reflectiveRegistrar = new ReflectiveRuntimeHintsRegistrar();
 
 		@Override
-		public void registerHints(RuntimeHints hints, ClassLoader classLoader) {
+		public void registerHints(RuntimeHints hints, @Nullable ClassLoader classLoader) {
 			this.reflectiveRegistrar.registerRuntimeHints(hints, WriteOperationHandler.class,
 					ReadOperationHandler.class);
 		}

module/spring-boot-webflux/src/main/java/org/springframework/boot/webflux/actuate/endpoint/web/AdditionalHealthEndpointPathsWebFluxHandlerMapping.java

@@ -20,7 +20,11 @@ import java.util.Collection;
 import java.util.Collections;
 import java.util.Set;
 
+import org.jspecify.annotations.Nullable;
+import reactor.core.publisher.Mono;
+
 import org.springframework.boot.actuate.endpoint.web.EndpointMapping;
+import org.springframework.boot.actuate.endpoint.web.EndpointMediaTypes;
 import org.springframework.boot.actuate.endpoint.web.ExposableWebEndpoint;
 import org.springframework.boot.actuate.endpoint.web.WebOperation;
 import org.springframework.boot.actuate.endpoint.web.WebOperationRequestPredicate;
@@ -42,19 +46,19 @@ public class AdditionalHealthEndpointPathsWebFluxHandlerMapping extends Abstract
 
 	private final EndpointMapping endpointMapping;
 
-	private final ExposableWebEndpoint healthEndpoint;
+	private final @Nullable ExposableWebEndpoint healthEndpoint;
 
 	private final Set<HealthEndpointGroup> groups;
 
 	public AdditionalHealthEndpointPathsWebFluxHandlerMapping(EndpointMapping endpointMapping,
-			ExposableWebEndpoint healthEndpoint, Set<HealthEndpointGroup> groups) {
-		super(endpointMapping, asList(healthEndpoint), null, null, false);
+			@Nullable ExposableWebEndpoint healthEndpoint, Set<HealthEndpointGroup> groups) {
+		super(endpointMapping, asList(healthEndpoint), new EndpointMediaTypes(), null, false);
 		this.endpointMapping = endpointMapping;
 		this.groups = groups;
 		this.healthEndpoint = healthEndpoint;
 	}
 
-	private static Collection<ExposableWebEndpoint> asList(ExposableWebEndpoint healthEndpoint) {
+	private static Collection<ExposableWebEndpoint> asList(@Nullable ExposableWebEndpoint healthEndpoint) {
 		return (healthEndpoint != null) ? Collections.singletonList(healthEndpoint) : Collections.emptyList();
 	}
 
@@ -90,7 +94,7 @@ public class AdditionalHealthEndpointPathsWebFluxHandlerMapping extends Abstract
 
 	@Override
 	protected LinksHandler getLinksHandler() {
-		return null;
+		return (exchange) -> Mono.empty();
 	}
 
 }

module/spring-boot-webflux/src/main/java/org/springframework/boot/webflux/actuate/endpoint/web/ControllerEndpointHandlerMapping.java

@@ -25,6 +25,8 @@ import java.util.LinkedHashMap;
 import java.util.Map;
 import java.util.Set;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.boot.actuate.endpoint.Access;
 import org.springframework.boot.actuate.endpoint.EndpointAccessResolver;
 import org.springframework.boot.actuate.endpoint.web.EndpointMapping;
@@ -58,7 +60,7 @@ public class ControllerEndpointHandlerMapping extends RequestMappingHandlerMappi
 
 	private final EndpointMapping endpointMapping;
 
-	private final CorsConfiguration corsConfiguration;
+	private final @Nullable CorsConfiguration corsConfiguration;
 
 	private final Map<Object, ExposableControllerEndpoint> handlers;
 
@@ -72,7 +74,7 @@ public class ControllerEndpointHandlerMapping extends RequestMappingHandlerMappi
 	 * @param corsConfiguration the CORS configuration for the endpoints or {@code null}
 	 */
 	public ControllerEndpointHandlerMapping(EndpointMapping endpointMapping,
-			Collection<ExposableControllerEndpoint> endpoints, CorsConfiguration corsConfiguration) {
+			Collection<ExposableControllerEndpoint> endpoints, @Nullable CorsConfiguration corsConfiguration) {
 		this(endpointMapping, endpoints, corsConfiguration, (endpointId, defaultAccess) -> Access.NONE);
 	}
 
@@ -85,7 +87,7 @@ public class ControllerEndpointHandlerMapping extends RequestMappingHandlerMappi
 	 * @param endpointAccessResolver resolver for endpoint access
 	 */
 	public ControllerEndpointHandlerMapping(EndpointMapping endpointMapping,
-			Collection<ExposableControllerEndpoint> endpoints, CorsConfiguration corsConfiguration,
+			Collection<ExposableControllerEndpoint> endpoints, @Nullable CorsConfiguration corsConfiguration,
 			EndpointAccessResolver endpointAccessResolver) {
 		Assert.notNull(endpointMapping, "'endpointMapping' must not be null");
 		Assert.notNull(endpoints, "'endpoints' must not be null");
@@ -110,6 +112,7 @@ public class ControllerEndpointHandlerMapping extends RequestMappingHandlerMappi
 	@Override
 	protected void registerHandlerMethod(Object handler, Method method, RequestMappingInfo mapping) {
 		ExposableControllerEndpoint endpoint = this.handlers.get(handler);
+		Assert.state(endpoint != null, "'endpoint' must not be null");
 		Access access = this.accessResolver.accessFor(endpoint.getEndpointId(), endpoint.getDefaultAccess());
 		if (access == Access.NONE) {
 			return;
@@ -157,7 +160,8 @@ public class ControllerEndpointHandlerMapping extends RequestMappingHandlerMappi
 	}
 
 	@Override
-	protected CorsConfiguration initCorsConfiguration(Object handler, Method method, RequestMappingInfo mapping) {
+	protected @Nullable CorsConfiguration initCorsConfiguration(Object handler, Method method,
+			RequestMappingInfo mapping) {
 		return this.corsConfiguration;
 	}
 

module/spring-boot-webflux/src/main/java/org/springframework/boot/webflux/actuate/endpoint/web/WebFluxEndpointHandlerMapping.java

@@ -20,6 +20,8 @@ import java.util.Collection;
 import java.util.Collections;
 import java.util.Map;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.aot.hint.BindingReflectionHintsRegistrar;
 import org.springframework.aot.hint.RuntimeHints;
 import org.springframework.aot.hint.RuntimeHintsRegistrar;
@@ -65,7 +67,7 @@ public class WebFluxEndpointHandlerMapping extends AbstractWebFluxEndpointHandle
 	 * @param shouldRegisterLinksMapping whether the links endpoint should be registered
 	 */
 	public WebFluxEndpointHandlerMapping(EndpointMapping endpointMapping, Collection<ExposableWebEndpoint> endpoints,
-			EndpointMediaTypes endpointMediaTypes, CorsConfiguration corsConfiguration,
+			EndpointMediaTypes endpointMediaTypes, @Nullable CorsConfiguration corsConfiguration,
 			EndpointLinksResolver linksResolver, boolean shouldRegisterLinksMapping) {
 		super(endpointMapping, endpoints, endpointMediaTypes, corsConfiguration, shouldRegisterLinksMapping);
 		this.linksResolver = linksResolver;
@@ -107,7 +109,7 @@ public class WebFluxEndpointHandlerMapping extends AbstractWebFluxEndpointHandle
 		private final BindingReflectionHintsRegistrar bindingRegistrar = new BindingReflectionHintsRegistrar();
 
 		@Override
-		public void registerHints(RuntimeHints hints, ClassLoader classLoader) {
+		public void registerHints(RuntimeHints hints, @Nullable ClassLoader classLoader) {
 			this.reflectiveRegistrar.registerRuntimeHints(hints, WebFluxLinksHandler.class);
 			this.bindingRegistrar.registerReflectionHints(hints.reflection(), Link.class);
 		}

module/spring-boot-webflux/src/main/java/org/springframework/boot/webflux/actuate/endpoint/web/package-info.java

@@ -17,4 +17,7 @@
 /**
  * Spring WebFlux support for actuator endpoints.
  */
+@NullMarked
 package org.springframework.boot.webflux.actuate.endpoint.web;
+
+import org.jspecify.annotations.NullMarked;

module/spring-boot-webflux/src/main/java/org/springframework/boot/webflux/actuate/exchanges/HttpExchangesWebFilter.java

@@ -19,6 +19,7 @@ package org.springframework.boot.webflux.actuate.exchanges;
 import java.security.Principal;
 import java.util.Set;
 
+import org.jspecify.annotations.Nullable;
 import reactor.core.publisher.Mono;
 
 import org.springframework.boot.actuate.web.exchanges.HttpExchange;
@@ -98,20 +99,20 @@ public class HttpExchangesWebFilter implements WebFilter, Ordered {
 	 */
 	private static class PrincipalAndSession {
 
-		private final Principal principal;
+		private final @Nullable Principal principal;
 
-		private final WebSession session;
+		private final @Nullable WebSession session;
 
 		PrincipalAndSession(Object[] zipped) {
 			this.principal = (zipped[0] != NONE) ? (Principal) zipped[0] : null;
 			this.session = (zipped[1] != NONE) ? (WebSession) zipped[1] : null;
 		}
 
-		Principal getPrincipal() {
+		@Nullable Principal getPrincipal() {
 			return this.principal;
 		}
 
-		String getSessionId() {
+		@Nullable String getSessionId() {
 			return (this.session != null && this.session.isStarted()) ? this.session.getId() : null;
 		}
 

module/spring-boot-webflux/src/main/java/org/springframework/boot/webflux/actuate/exchanges/RecordableServerHttpRequest.java

@@ -24,6 +24,8 @@ import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.boot.actuate.web.exchanges.RecordableHttpRequest;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.server.reactive.ServerHttpRequest;
@@ -41,7 +43,7 @@ class RecordableServerHttpRequest implements RecordableHttpRequest {
 
 	private final URI uri;
 
-	private final String remoteAddress;
+	private final @Nullable String remoteAddress;
 
 	RecordableServerHttpRequest(ServerHttpRequest request) {
 		this.method = request.getMethod().name();
@@ -50,7 +52,7 @@ class RecordableServerHttpRequest implements RecordableHttpRequest {
 		this.remoteAddress = getRemoteAddress(request);
 	}
 
-	private static String getRemoteAddress(ServerHttpRequest request) {
+	private static @Nullable String getRemoteAddress(ServerHttpRequest request) {
 		InetSocketAddress remoteAddress = request.getRemoteAddress();
 		InetAddress address = (remoteAddress != null) ? remoteAddress.getAddress() : null;
 		return (address != null) ? address.toString() : null;
@@ -74,7 +76,7 @@ class RecordableServerHttpRequest implements RecordableHttpRequest {
 	}
 
 	@Override
-	public String getRemoteAddress() {
+	public @Nullable String getRemoteAddress() {
 		return this.remoteAddress;
 	}
 

module/spring-boot-webflux/src/main/java/org/springframework/boot/webflux/actuate/exchanges/package-info.java

@@ -19,4 +19,7 @@
  *
  * @see org.springframework.boot.actuate.web.exchanges.HttpExchangeRepository
  */
+@NullMarked
 package org.springframework.boot.webflux.actuate.exchanges;
+
+import org.jspecify.annotations.NullMarked;

module/spring-boot-webflux/src/main/java/org/springframework/boot/webflux/actuate/mappings/DispatcherHandlerMappingDescription.java

@@ -16,6 +16,8 @@
 
 package org.springframework.boot.webflux.actuate.mappings;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.web.reactive.DispatcherHandler;
 
 /**
@@ -30,9 +32,10 @@ public class DispatcherHandlerMappingDescription {
 
 	private final String handler;
 
-	private final DispatcherHandlerMappingDetails details;
+	private final @Nullable DispatcherHandlerMappingDetails details;
 
-	DispatcherHandlerMappingDescription(String predicate, String handler, DispatcherHandlerMappingDetails details) {
+	DispatcherHandlerMappingDescription(String predicate, String handler,
+			@Nullable DispatcherHandlerMappingDetails details) {
 		this.predicate = predicate;
 		this.handler = handler;
 		this.details = details;
@@ -46,7 +49,7 @@ public class DispatcherHandlerMappingDescription {
 		return this.predicate;
 	}
 
-	public DispatcherHandlerMappingDetails getDetails() {
+	public @Nullable DispatcherHandlerMappingDetails getDetails() {
 		return this.details;
 	}
 

module/spring-boot-webflux/src/main/java/org/springframework/boot/webflux/actuate/mappings/DispatcherHandlerMappingDetails.java

@@ -16,6 +16,8 @@
 
 package org.springframework.boot.webflux.actuate.mappings;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.boot.actuate.web.mappings.HandlerMethodDescription;
 import org.springframework.web.reactive.DispatcherHandler;
 
@@ -27,33 +29,33 @@ import org.springframework.web.reactive.DispatcherHandler;
  */
 public class DispatcherHandlerMappingDetails {
 
-	private HandlerMethodDescription handlerMethod;
+	private @Nullable HandlerMethodDescription handlerMethod;
 
-	private HandlerFunctionDescription handlerFunction;
+	private @Nullable HandlerFunctionDescription handlerFunction;
 
-	private RequestMappingConditionsDescription requestMappingConditions;
+	private @Nullable RequestMappingConditionsDescription requestMappingConditions;
 
-	public HandlerMethodDescription getHandlerMethod() {
+	public @Nullable HandlerMethodDescription getHandlerMethod() {
 		return this.handlerMethod;
 	}
 
-	void setHandlerMethod(HandlerMethodDescription handlerMethod) {
+	void setHandlerMethod(@Nullable HandlerMethodDescription handlerMethod) {
 		this.handlerMethod = handlerMethod;
 	}
 
-	public HandlerFunctionDescription getHandlerFunction() {
+	public @Nullable HandlerFunctionDescription getHandlerFunction() {
 		return this.handlerFunction;
 	}
 
-	void setHandlerFunction(HandlerFunctionDescription handlerFunction) {
+	void setHandlerFunction(@Nullable HandlerFunctionDescription handlerFunction) {
 		this.handlerFunction = handlerFunction;
 	}
 
-	public RequestMappingConditionsDescription getRequestMappingConditions() {
+	public @Nullable RequestMappingConditionsDescription getRequestMappingConditions() {
 		return this.requestMappingConditions;
 	}
 
-	void setRequestMappingConditions(RequestMappingConditionsDescription requestMappingConditions) {
+	void setRequestMappingConditions(@Nullable RequestMappingConditionsDescription requestMappingConditions) {
 		this.requestMappingConditions = requestMappingConditions;
 	}
 

module/spring-boot-webflux/src/main/java/org/springframework/boot/webflux/actuate/mappings/DispatcherHandlersMappingDescriptionProvider.java

@@ -18,6 +18,7 @@ package org.springframework.boot.webflux.actuate.mappings;
 
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -25,6 +26,7 @@ import java.util.Map.Entry;
 import java.util.function.Function;
 import java.util.stream.Stream;
 
+import org.jspecify.annotations.Nullable;
 import reactor.core.publisher.Mono;
 
 import org.springframework.aot.hint.BindingReflectionHintsRegistrar;
@@ -78,7 +80,11 @@ public class DispatcherHandlersMappingDescriptionProvider implements MappingDesc
 	}
 
 	private List<DispatcherHandlerMappingDescription> describeMappings(DispatcherHandler dispatcherHandler) {
-		return dispatcherHandler.getHandlerMappings().stream().flatMap(this::describe).toList();
+		List<HandlerMapping> handlerMappings = dispatcherHandler.getHandlerMappings();
+		if (handlerMappings == null) {
+			return Collections.emptyList();
+		}
+		return handlerMappings.stream().flatMap(this::describe).toList();
 	}
 
 	@SuppressWarnings("unchecked")
@@ -202,7 +208,7 @@ public class DispatcherHandlersMappingDescriptionProvider implements MappingDesc
 		private final BindingReflectionHintsRegistrar bindingRegistrar = new BindingReflectionHintsRegistrar();
 
 		@Override
-		public void registerHints(RuntimeHints hints, ClassLoader classLoader) {
+		public void registerHints(RuntimeHints hints, @Nullable ClassLoader classLoader) {
 			this.bindingRegistrar.registerReflectionHints(hints.reflection(),
 					DispatcherHandlerMappingDescription.class);
 		}

module/spring-boot-webflux/src/main/java/org/springframework/boot/webflux/actuate/mappings/RequestMappingConditionsDescription.java

@@ -21,6 +21,8 @@ import java.util.List;
 import java.util.Set;
 import java.util.stream.Collectors;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.web.bind.annotation.RequestMethod;
 import org.springframework.web.reactive.result.condition.MediaTypeExpression;
 import org.springframework.web.reactive.result.condition.NameValueExpression;
@@ -131,7 +133,7 @@ public class RequestMappingConditionsDescription {
 
 		private final String name;
 
-		private final Object value;
+		private final @Nullable Object value;
 
 		private final boolean negated;
 
@@ -145,7 +147,7 @@ public class RequestMappingConditionsDescription {
 			return this.name;
 		}
 
-		public Object getValue() {
+		public @Nullable Object getValue() {
 			return this.value;
 		}
 

module/spring-boot-webflux/src/main/java/org/springframework/boot/webflux/actuate/mappings/package-info.java

@@ -17,4 +17,7 @@
 /**
  * Actuator reactive request mappings support.
  */
+@NullMarked
 package org.springframework.boot.webflux.actuate.mappings;
+
+import org.jspecify.annotations.NullMarked;

module/spring-boot-webflux/src/main/java/org/springframework/boot/webflux/autoconfigure/ReactiveMultipartProperties.java

@@ -19,6 +19,8 @@ package org.springframework.boot.webflux.autoconfigure;
 import java.nio.charset.Charset;
 import java.nio.charset.StandardCharsets;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.boot.context.properties.ConfigurationProperties;
 import org.springframework.http.codec.multipart.DefaultPartHttpMessageReader;
 import org.springframework.http.codec.multipart.PartEventHttpMessageReader;
@@ -64,7 +66,7 @@ public class ReactiveMultipartProperties {
 	 * directory named 'spring-multipart' created under the system temporary directory.
 	 * Ignored when using the PartEvent streaming support.
 	 */
-	private String fileStorageDirectory;
+	private @Nullable String fileStorageDirectory;
 
 	/**
 	 * Character set used to decode headers.
@@ -103,11 +105,11 @@ public class ReactiveMultipartProperties {
 		this.maxParts = maxParts;
 	}
 
-	public String getFileStorageDirectory() {
+	public @Nullable String getFileStorageDirectory() {
 		return this.fileStorageDirectory;
 	}
 
-	public void setFileStorageDirectory(String fileStorageDirectory) {
+	public void setFileStorageDirectory(@Nullable String fileStorageDirectory) {
 		this.fileStorageDirectory = fileStorageDirectory;
 	}
 

module/spring-boot-webflux/src/main/java/org/springframework/boot/webflux/autoconfigure/ResourceChainResourceHandlerRegistrationCustomizer.java

@@ -17,6 +17,7 @@
 package org.springframework.boot.webflux.autoconfigure;
 
 import org.springframework.boot.autoconfigure.web.WebProperties.Resources;
+import org.springframework.util.Assert;
 import org.springframework.web.reactive.config.ResourceChainRegistration;
 import org.springframework.web.reactive.config.ResourceHandlerRegistration;
 import org.springframework.web.reactive.resource.EncodedResourceResolver;
@@ -58,6 +59,7 @@ class ResourceChainResourceHandlerRegistrationCustomizer implements ResourceHand
 		if (properties.getFixed().isEnabled()) {
 			String version = properties.getFixed().getVersion();
 			String[] paths = properties.getFixed().getPaths();
+			Assert.state(version != null, "'version' must not be null");
 			resolver.addFixedVersionStrategy(version, paths);
 		}
 		if (properties.getContent().isEnabled()) {

module/spring-boot-webflux/src/main/java/org/springframework/boot/webflux/autoconfigure/WebFluxAutoConfiguration.java

@@ -18,6 +18,7 @@ package org.springframework.boot.webflux.autoconfigure;
 
 import java.time.Duration;
 import java.util.List;
+import java.util.Locale;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
@@ -65,7 +66,9 @@ import org.springframework.core.env.Environment;
 import org.springframework.core.task.AsyncTaskExecutor;
 import org.springframework.format.FormatterRegistry;
 import org.springframework.format.support.FormattingConversionService;
+import org.springframework.http.CacheControl;
 import org.springframework.http.codec.ServerCodecConfigurer;
+import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 import org.springframework.validation.Validator;
 import org.springframework.web.accept.ApiVersionParser;
@@ -137,7 +140,7 @@ public final class WebFluxAutoConfiguration {
 	static class WelcomePageConfiguration {
 
 		@Bean
-		RouterFunctionMapping welcomePageRouterFunctionMapping(ApplicationContext applicationContext,
+		@Nullable RouterFunctionMapping welcomePageRouterFunctionMapping(ApplicationContext applicationContext,
 				WebFluxProperties webFluxProperties, WebProperties webProperties) {
 			String[] staticLocations = webProperties.getResources().getStaticLocations();
 			WelcomePageRouterFunctionFactory factory = new WelcomePageRouterFunctionFactory(
@@ -258,7 +261,10 @@ public final class WebFluxAutoConfiguration {
 			if (cachePeriod != null && cacheControl.getMaxAge() == null) {
 				cacheControl.setMaxAge(cachePeriod);
 			}
-			registration.setCacheControl(cacheControl.toHttpCacheControl());
+			CacheControl httpCacheControl = cacheControl.toHttpCacheControl();
+			if (httpCacheControl != null) {
+				registration.setCacheControl(httpCacheControl);
+			}
 			registration.setUseLastModified(this.resourceProperties.getCache().isUseLastModified());
 		}
 
@@ -310,7 +316,7 @@ public final class WebFluxAutoConfiguration {
 
 		private final ServerProperties serverProperties;
 
-		private final WebFluxRegistrations webFluxRegistrations;
+		private final @Nullable WebFluxRegistrations webFluxRegistrations;
 
 		EnableWebFluxConfiguration(WebFluxProperties webFluxProperties, WebProperties webProperties,
 				ServerProperties serverProperties, ObjectProvider<WebFluxRegistrations> webFluxRegistrations) {
@@ -340,7 +346,9 @@ public final class WebFluxAutoConfiguration {
 							getClass().getClassLoader())) {
 				return super.webFluxValidator();
 			}
-			return ValidatorAdapter.get(getApplicationContext(), getValidator());
+			ApplicationContext applicationContext = getApplicationContext();
+			Assert.state(applicationContext != null, "'applicationContext' must not be null");
+			return ValidatorAdapter.get(applicationContext, getValidator());
 		}
 
 		@Override
@@ -369,11 +377,13 @@ public final class WebFluxAutoConfiguration {
 		@Override
 		@ConditionalOnMissingBean(name = WebHttpHandlerBuilder.LOCALE_CONTEXT_RESOLVER_BEAN_NAME)
 		public LocaleContextResolver localeContextResolver() {
+			Locale locale = this.webProperties.getLocale();
 			if (this.webProperties.getLocaleResolver() == WebProperties.LocaleResolver.FIXED) {
-				return new FixedLocaleContextResolver(this.webProperties.getLocale());
+				Assert.state(locale != null, "'locale' must not be null");
+				return new FixedLocaleContextResolver(locale);
 			}
 			AcceptHeaderLocaleContextResolver localeContextResolver = new AcceptHeaderLocaleContextResolver();
-			localeContextResolver.setDefaultLocale(this.webProperties.getLocale());
+			localeContextResolver.setDefaultLocale(locale);
 			return localeContextResolver;
 		}
 

module/spring-boot-webflux/src/main/java/org/springframework/boot/webflux/autoconfigure/WebFluxProperties.java

@@ -20,6 +20,8 @@ import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.boot.context.properties.ConfigurationProperties;
 import org.springframework.boot.context.properties.bind.Name;
 import org.springframework.http.MediaType;
@@ -38,7 +40,7 @@ public class WebFluxProperties {
 	/**
 	 * Base path for all web handlers.
 	 */
-	private String basePath;
+	private @Nullable String basePath;
 
 	private final Format format = new Format();
 
@@ -56,15 +58,15 @@ public class WebFluxProperties {
 	 */
 	private String webjarsPathPattern = "/webjars/**";
 
-	public String getBasePath() {
+	public @Nullable String getBasePath() {
 		return this.basePath;
 	}
 
-	public void setBasePath(String basePath) {
+	public void setBasePath(@Nullable String basePath) {
 		this.basePath = cleanBasePath(basePath);
 	}
 
-	private String cleanBasePath(String basePath) {
+	private @Nullable String cleanBasePath(@Nullable String basePath) {
 		String candidate = null;
 		if (StringUtils.hasLength(basePath)) {
 			candidate = basePath.strip();
@@ -114,41 +116,41 @@ public class WebFluxProperties {
 		 * Date format to use, for example 'dd/MM/yyyy'. Used for formatting of
 		 * java.util.Date and java.time.LocalDate.
 		 */
-		private String date;
+		private @Nullable String date;
 
 		/**
 		 * Time format to use, for example 'HH:mm:ss'. Used for formatting of java.time's
 		 * LocalTime and OffsetTime.
 		 */
-		private String time;
+		private @Nullable String time;
 
 		/**
 		 * Date-time format to use, for example 'yyyy-MM-dd HH:mm:ss'. Used for formatting
 		 * of java.time's LocalDateTime, OffsetDateTime, and ZonedDateTime.
 		 */
-		private String dateTime;
+		private @Nullable String dateTime;
 
-		public String getDate() {
+		public @Nullable String getDate() {
 			return this.date;
 		}
 
-		public void setDate(String date) {
+		public void setDate(@Nullable String date) {
 			this.date = date;
 		}
 
-		public String getTime() {
+		public @Nullable String getTime() {
 			return this.time;
 		}
 
-		public void setTime(String time) {
+		public void setTime(@Nullable String time) {
 			this.time = time;
 		}
 
-		public String getDateTime() {
+		public @Nullable String getDateTime() {
 			return this.dateTime;
 		}
 
-		public void setDateTime(String dateTime) {
+		public void setDateTime(@Nullable String dateTime) {
 			this.dateTime = dateTime;
 		}
 
@@ -176,58 +178,58 @@ public class WebFluxProperties {
 		/**
 		 * Whether the API version is required with each request.
 		 */
-		private Boolean required;
+		private @Nullable Boolean required;
 
 		/**
 		 * Default version that should be used for each request.
 		 */
 		@Name("default")
-		private String defaultVersion;
+		private @Nullable String defaultVersion;
 
 		/**
 		 * Supported versions.
 		 */
-		private List<String> supported;
+		private @Nullable List<String> supported;
 
 		/**
 		 * Whether supported versions should be detected from controllers.
 		 */
-		private Boolean detectSupported;
+		private @Nullable Boolean detectSupported;
 
 		/**
 		 * How version details should be inserted into requests.
 		 */
 		private final Use use = new Use();
 
-		public Boolean getRequired() {
+		public @Nullable Boolean getRequired() {
 			return this.required;
 		}
 
-		public void setRequired(Boolean required) {
+		public void setRequired(@Nullable Boolean required) {
 			this.required = required;
 		}
 
-		public String getDefaultVersion() {
+		public @Nullable String getDefaultVersion() {
 			return this.defaultVersion;
 		}
 
-		public void setDefaultVersion(String defaultVersion) {
+		public void setDefaultVersion(@Nullable String defaultVersion) {
 			this.defaultVersion = defaultVersion;
 		}
 
-		public List<String> getSupported() {
+		public @Nullable List<String> getSupported() {
 			return this.supported;
 		}
 
-		public void setSupported(List<String> supported) {
+		public void setSupported(@Nullable List<String> supported) {
 			this.supported = supported;
 		}
 
-		public Boolean getDetectSupported() {
+		public @Nullable Boolean getDetectSupported() {
 			return this.detectSupported;
 		}
 
-		public void setDetectSupported(Boolean detectSupported) {
+		public void setDetectSupported(@Nullable Boolean detectSupported) {
 			this.detectSupported = detectSupported;
 		}
 
@@ -240,44 +242,44 @@ public class WebFluxProperties {
 			/**
 			 * Use the HTTP header with the given name to obtain the version.
 			 */
-			private String header;
+			private @Nullable String header;
 
 			/**
 			 * Use the query parameter with the given name to obtain the version.
 			 */
-			private String queryParameter;
+			private @Nullable String queryParameter;
 
 			/**
 			 * Use the path segment at the given index to obtain the version.
 			 */
-			private Integer pathSegment;
+			private @Nullable Integer pathSegment;
 
 			/**
 			 * Use the media type parameter with the given name to obtain the version.
 			 */
 			private Map<MediaType, String> mediaTypeParameter = new LinkedHashMap<>();
 
-			public String getHeader() {
+			public @Nullable String getHeader() {
 				return this.header;
 			}
 
-			public void setHeader(String header) {
+			public void setHeader(@Nullable String header) {
 				this.header = header;
 			}
 
-			public String getQueryParameter() {
+			public @Nullable String getQueryParameter() {
 				return this.queryParameter;
 			}
 
-			public void setQueryParameter(String queryParameter) {
+			public void setQueryParameter(@Nullable String queryParameter) {
 				this.queryParameter = queryParameter;
 			}
 
-			public Integer getPathSegment() {
+			public @Nullable Integer getPathSegment() {
 				return this.pathSegment;
 			}
 
-			public void setPathSegment(Integer pathSegment) {
+			public void setPathSegment(@Nullable Integer pathSegment) {
 				this.pathSegment = pathSegment;
 			}
 

module/spring-boot-webflux/src/main/java/org/springframework/boot/webflux/autoconfigure/WebFluxRegistrations.java

@@ -16,6 +16,8 @@
 
 package org.springframework.boot.webflux.autoconfigure;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.web.reactive.result.method.annotation.RequestMappingHandlerAdapter;
 import org.springframework.web.reactive.result.method.annotation.RequestMappingHandlerMapping;
 
@@ -38,7 +40,7 @@ public interface WebFluxRegistrations {
 	 * processed by the WebFlux configuration.
 	 * @return the custom {@link RequestMappingHandlerMapping} instance
 	 */
-	default RequestMappingHandlerMapping getRequestMappingHandlerMapping() {
+	default @Nullable RequestMappingHandlerMapping getRequestMappingHandlerMapping() {
 		return null;
 	}
 
@@ -47,7 +49,7 @@ public interface WebFluxRegistrations {
 	 * processed by the WebFlux configuration.
 	 * @return the custom {@link RequestMappingHandlerAdapter} instance
 	 */
-	default RequestMappingHandlerAdapter getRequestMappingHandlerAdapter() {
+	default @Nullable RequestMappingHandlerAdapter getRequestMappingHandlerAdapter() {
 		return null;
 	}
 

module/spring-boot-webflux/src/main/java/org/springframework/boot/webflux/autoconfigure/WebSessionIdResolverAutoConfiguration.java

@@ -76,6 +76,11 @@ public final class WebSessionIdResolverAutoConfiguration {
 		map.from(cookie::getSecure).to(builder::secure);
 		map.from(cookie::getMaxAge).to(builder::maxAge);
 		map.from(cookie::getPartitioned).to(builder::partitioned);
+		setSameSite(builder, map, cookie);
+	}
+
+	@SuppressWarnings("NullAway") // Lambda isn't detected with the correct nullability
+	private void setSameSite(ResponseCookieBuilder builder, PropertyMapper map, Cookie cookie) {
 		map.from(cookie::getSameSite).as(SameSite::attributeValue).to(builder::sameSite);
 	}
 

module/spring-boot-webflux/src/main/java/org/springframework/boot/webflux/autoconfigure/WelcomePageRouterFunctionFactory.java

@@ -18,6 +18,8 @@ package org.springframework.boot.webflux.autoconfigure;
 
 import java.util.Arrays;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.boot.autoconfigure.template.TemplateAvailabilityProviders;
 import org.springframework.context.ApplicationContext;
 import org.springframework.core.io.Resource;
@@ -41,7 +43,7 @@ final class WelcomePageRouterFunctionFactory {
 
 	private final String staticPathPattern;
 
-	private final Resource welcomePage;
+	private final @Nullable Resource welcomePage;
 
 	private final boolean welcomePageTemplateExists;
 
@@ -52,7 +54,7 @@ final class WelcomePageRouterFunctionFactory {
 		this.welcomePageTemplateExists = welcomeTemplateExists(templateAvailabilityProviders, applicationContext);
 	}
 
-	private Resource getWelcomePage(ResourceLoader resourceLoader, String[] staticLocations) {
+	private @Nullable Resource getWelcomePage(ResourceLoader resourceLoader, String[] staticLocations) {
 		return Arrays.stream(staticLocations)
 			.map((location) -> getIndexHtml(resourceLoader, location))
 			.filter(this::isReadable)
@@ -78,7 +80,7 @@ final class WelcomePageRouterFunctionFactory {
 		return templateAvailabilityProviders.getProvider("index", applicationContext) != null;
 	}
 
-	RouterFunction<ServerResponse> createRouterFunction() {
+	@Nullable RouterFunction<ServerResponse> createRouterFunction() {
 		if (this.welcomePage != null && "/**".equals(this.staticPathPattern)) {
 			return RouterFunctions.route(GET("/").and(accept(MediaType.TEXT_HTML)),
 					(req) -> ServerResponse.ok().contentType(MediaType.TEXT_HTML).bodyValue(this.welcomePage));

module/spring-boot-webflux/src/main/java/org/springframework/boot/webflux/autoconfigure/actuate/endpoint/web/package-info.java

@@ -17,4 +17,7 @@
 /**
  * Auto-configuration for Spring WebFlux actuator web endpoint support.
  */
+@NullMarked
 package org.springframework.boot.webflux.autoconfigure.actuate.endpoint.web;
+
+import org.jspecify.annotations.NullMarked;

module/spring-boot-webflux/src/main/java/org/springframework/boot/webflux/autoconfigure/actuate/web/package-info.java

@@ -17,4 +17,7 @@
 /**
  * Auto-configuration for WebFlux-based actuator web concerns.
  */
+@NullMarked
 package org.springframework.boot.webflux.autoconfigure.actuate.web;
+
+import org.jspecify.annotations.NullMarked;

module/spring-boot-webflux/src/main/java/org/springframework/boot/webflux/autoconfigure/error/AbstractErrorWebExceptionHandler.java

@@ -22,6 +22,7 @@ import java.util.List;
 import java.util.Map;
 
 import org.apache.commons.logging.Log;
+import org.jspecify.annotations.Nullable;
 import reactor.core.publisher.Mono;
 
 import org.springframework.beans.factory.InitializingBean;
@@ -135,7 +136,7 @@ public abstract class AbstractErrorWebExceptionHandler implements ErrorWebExcept
 	 * @param request the source request
 	 * @return the error
 	 */
-	protected Throwable getError(ServerRequest request) {
+	protected @Nullable Throwable getError(ServerRequest request) {
 		return this.errorAttributes.getError(request);
 	}
 
@@ -208,7 +209,7 @@ public abstract class AbstractErrorWebExceptionHandler implements ErrorWebExcept
 		return this.templateAvailabilityProviders.getProvider(viewName, this.applicationContext) != null;
 	}
 
-	private Resource resolveResource(String viewName) {
+	private @Nullable Resource resolveResource(String viewName) {
 		for (String location : this.resources.getStaticLocations()) {
 			try {
 				Resource resource = this.applicationContext.getResource(location);
@@ -261,7 +262,7 @@ public abstract class AbstractErrorWebExceptionHandler implements ErrorWebExcept
 		return responseBody.bodyValue(builder.toString());
 	}
 
-	private String htmlEscape(Object input) {
+	private @Nullable String htmlEscape(@Nullable Object input) {
 		return (input != null) ? HtmlUtils.htmlEscape(input.toString()) : null;
 	}
 

module/spring-boot-webflux/src/main/java/org/springframework/boot/webflux/autoconfigure/error/package-info.java

@@ -17,4 +17,7 @@
 /**
  * Auto-configuration for Spring WebFlux error handling.
  */
+@NullMarked
 package org.springframework.boot.webflux.autoconfigure.error;
+
+import org.jspecify.annotations.NullMarked;

module/spring-boot-webflux/src/main/java/org/springframework/boot/webflux/autoconfigure/package-info.java

@@ -17,4 +17,7 @@
 /**
  * Auto-configuration for reactive web servers and Spring WebFlux.
  */
+@NullMarked
 package org.springframework.boot.webflux.autoconfigure;
+
+import org.jspecify.annotations.NullMarked;

module/spring-boot-webflux/src/main/java/org/springframework/boot/webflux/error/ErrorAttributes.java

@@ -19,6 +19,8 @@ package org.springframework.boot.webflux.error;
 import java.util.Collections;
 import java.util.Map;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.boot.web.error.ErrorAttributeOptions;
 import org.springframework.web.reactive.function.server.ServerRequest;
 import org.springframework.web.reactive.function.server.ServerResponse;
@@ -51,7 +53,7 @@ public interface ErrorAttributes {
 	 * @param request the source ServerRequest
 	 * @return the {@link Exception} that caused the error or {@code null}
 	 */
-	Throwable getError(ServerRequest request);
+	@Nullable Throwable getError(ServerRequest request);
 
 	/**
 	 * Store the given error information in the current {@link ServerWebExchange}.

module/spring-boot-webflux/src/main/java/org/springframework/boot/webflux/error/package-info.java

@@ -17,4 +17,7 @@
 /**
  * Spring WebFlux error handling infrastructure.
  */
+@NullMarked
 package org.springframework.boot.webflux.error;
+
+import org.jspecify.annotations.NullMarked;

module/spring-boot-webflux/src/main/java/org/springframework/boot/webflux/filter/package-info.java

@@ -17,4 +17,7 @@
 /**
  * Spring Boot specific {@link org.springframework.web.server.WebFilter} implementations.
  */
+@NullMarked
 package org.springframework.boot.webflux.filter;
+
+import org.jspecify.annotations.NullMarked;