Specify generic type nullness in spring-webflux

See spring-projectsgh-34140

spring-webflux/src/main/java/org/springframework/web/reactive/config/WebFluxConfigurerComposite.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -63,11 +63,13 @@ public void addFormatters(FormatterRegistry registry) {
 	}
 
 	@Override
+	@SuppressWarnings("NullAway") // https://github.com/uber/NullAway/issues/1128
 	public @Nullable Validator getValidator() {
 		return createSingleBean(WebFluxConfigurer::getValidator, Validator.class);
 	}
 
 	@Override
+	@SuppressWarnings("NullAway") // https://github.com/uber/NullAway/issues/1128
 	public @Nullable MessageCodesResolver getMessageCodesResolver() {
 		return createSingleBean(WebFluxConfigurer::getMessageCodesResolver, MessageCodesResolver.class);
 	}
@@ -115,11 +117,12 @@ public void addResourceHandlers(ResourceHandlerRegistry registry) {
 	}
 
 	@Override
+	@SuppressWarnings("NullAway") // https://github.com/uber/NullAway/issues/1128
 	public @Nullable WebSocketService getWebSocketService() {
 		return createSingleBean(WebFluxConfigurer::getWebSocketService, WebSocketService.class);
 	}
 
-	private <T> @Nullable T createSingleBean(Function<WebFluxConfigurer, T> factory, Class<T> beanType) {
+	private <T> @Nullable T createSingleBean(Function<WebFluxConfigurer, @Nullable T> factory, Class<T> beanType) {
 		List<T> result = this.delegates.stream().map(factory).filter(Objects::nonNull).toList();
 		if (result.isEmpty()) {
 			return null;

spring-webflux/src/main/java/org/springframework/web/reactive/function/client/DefaultClientResponse.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -232,7 +232,8 @@ public Mono<WebClientResponseException> createException() {
 				});
 	}
 
-	private Function<ResolvableType, ?> initDecodeFunction(byte[] body, @Nullable MediaType contentType) {
+	@SuppressWarnings("NullAway") // https://github.com/uber/NullAway/issues/1126
+	private Function<ResolvableType, ? extends @Nullable Object> initDecodeFunction(byte[] body, @Nullable MediaType contentType) {
 		return targetType -> {
 			if (ObjectUtils.isEmpty(body)) {
 				return null;

spring-webflux/src/main/java/org/springframework/web/reactive/result/condition/CompositeRequestCondition.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -79,20 +79,21 @@ public boolean isEmpty() {
 	/**
 	 * Return the underlying conditions, possibly empty but never {@code null}.
 	 */
-	public List<RequestCondition<?>> getConditions() {
+	public List<@Nullable RequestCondition<?>> getConditions() {
 		return unwrap();
 	}
 
-	private List<RequestCondition<?>> unwrap() {
-		List<RequestCondition<?>> result = new ArrayList<>();
+	private List<@Nullable RequestCondition<?>> unwrap() {
+		List<@Nullable RequestCondition<?>> result = new ArrayList<>();
 		for (RequestConditionHolder holder : this.requestConditions) {
 			result.add(holder.getCondition());
 		}
 		return result;
 	}
 
 	@Override
-	protected Collection<?> getContent() {
+	@SuppressWarnings("NullAway") // https://github.com/uber/NullAway/issues/1126
+	protected Collection<? extends @Nullable Object> getContent() {
 		return (!isEmpty() ? getConditions() : Collections.emptyList());
 	}
 
@@ -150,10 +151,11 @@ private void assertNumberOfConditions(CompositeRequestCondition other) {
 		}
 		RequestConditionHolder[] matchingConditions = new RequestConditionHolder[getLength()];
 		for (int i = 0; i < getLength(); i++) {
-			matchingConditions[i] = this.requestConditions[i].getMatchingCondition(exchange);
-			if (matchingConditions[i] == null) {
+			RequestConditionHolder matchingCondition = this.requestConditions[i].getMatchingCondition(exchange);
+			if (matchingCondition == null) {
 				return null;
 			}
+			matchingConditions[i] = matchingCondition;
 		}
 		return new CompositeRequestCondition(matchingConditions);
 	}

spring-webflux/src/main/java/org/springframework/web/reactive/result/method/annotation/RequestMappingHandlerAdapter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -314,7 +314,7 @@ private Mono<HandlerResult> handleException(
 					Throwable cause = exToExpose.getCause();
 					exToExpose = (cause != exToExpose ? cause : null);
 				}
-				Object[] arguments = new Object[exceptions.size() + 1];
+				@Nullable Object[] arguments = new Object[exceptions.size() + 1];
 				exceptions.toArray(arguments);  // efficient arraycopy call in ArrayList
 				arguments[arguments.length - 1] = handlerMethod;
 

spring-webflux/src/main/java/org/springframework/web/reactive/result/method/annotation/RequestMappingHandlerMapping.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -306,12 +306,12 @@ protected RequestMappingInfo createRequestMappingInfo(
 	 * Resolve placeholder values in the given array of patterns.
 	 * @return a new array with updated patterns
 	 */
-	protected String[] resolveEmbeddedValuesInPatterns(String[] patterns) {
+	protected @Nullable String[] resolveEmbeddedValuesInPatterns(String[] patterns) {
 		if (this.embeddedValueResolver == null) {
 			return patterns;
 		}
 		else {
-			String[] resolvedPatterns = new String[patterns.length];
+			@Nullable String[] resolvedPatterns = new String[patterns.length];
 			for (int i = 0; i < patterns.length; i++) {
 				resolvedPatterns[i] = this.embeddedValueResolver.resolveStringValue(patterns[i]);
 			}

spring-webflux/src/main/java/org/springframework/web/reactive/result/view/BindStatus.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,6 +19,7 @@
 import java.beans.PropertyEditor;
 import java.util.Arrays;
 import java.util.List;
+import java.util.Objects;
 
 import org.jspecify.annotations.Nullable;
 
@@ -58,7 +59,7 @@ public class BindStatus {
 
 	private final @Nullable Errors errors;
 
-	private final String[] errorCodes;
+	private final @Nullable String[] errorCodes;
 
 	private String @Nullable [] errorMessages;
 
@@ -162,8 +163,8 @@ else if (this.expression.endsWith("*")) {
 	/**
 	 * Extract the error codes from the ObjectError list.
 	 */
-	private static String[] initErrorCodes(List<? extends ObjectError> objectErrors) {
-		String[] errorCodes = new String[objectErrors.size()];
+	private static @Nullable String[] initErrorCodes(List<? extends ObjectError> objectErrors) {
+		@Nullable String[] errorCodes = new String[objectErrors.size()];
 		for (int i = 0; i < objectErrors.size(); i++) {
 			ObjectError error = objectErrors.get(i);
 			errorCodes[i] = error.getCode();
@@ -247,15 +248,17 @@ public boolean isError() {
 	 * Return the error codes for the field or object, if any.
 	 * Returns an empty array instead of null if none.
 	 */
-	public String[] getErrorCodes() {
+	public @Nullable String[] getErrorCodes() {
 		return this.errorCodes;
 	}
 
 	/**
 	 * Return the first error codes for the field or object, if any.
 	 */
 	public String getErrorCode() {
-		return (!ObjectUtils.isEmpty(this.errorCodes) ? this.errorCodes[0] : "");
+		return (!ObjectUtils.isEmpty(this.errorCodes) ? Objects.requireNonNull(this.errorCodes[0],
+
+				"Error code must not be null") : "");
 	}
 
 	/**