Refine null-safety in the spring-core module

Closes gh-34150

spring-core-test/src/main/java/org/springframework/aot/agent/InstrumentedMethod.java

@@ -173,7 +173,6 @@ enum InstrumentedMethod {
 	/**
 	 * {@link Class#getField(String)}.
 	 */
-	@SuppressWarnings("NullAway")
 	CLASS_GETFIELD(Class.class, "getField", HintType.REFLECTION,
 			invocation -> {
 				Field field = invocation.getReturnValue();
@@ -181,7 +180,7 @@ enum InstrumentedMethod {
 					return runtimeHints -> false;
 				}
 				return reflection().onType(field.getDeclaringClass())
-						.or(reflection().onField(invocation.getReturnValue()));
+						.or(reflection().onField(field));
 			}),
 
 	/**

spring-core/src/main/java/org/springframework/util/ClassUtils.java

@@ -558,7 +558,7 @@ public abstract class ClassUtils {
 	 * @param clazz the class to check
 	 * @return the original class, or a primitive wrapper for the original primitive type
 	 */
-	@SuppressWarnings("NullAway")
+	@SuppressWarnings("NullAway") // Dataflow analysis limitation
 	public static Class<?> resolvePrimitiveIfNecessary(Class<?> clazz) {
 		Assert.notNull(clazz, "Class must not be null");
 		return (clazz.isPrimitive() && clazz != void.class ? primitiveTypeToWrapperMap.get(clazz) : clazz);

spring-core/src/main/java/org/springframework/util/InvalidMimeTypeException.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,12 +16,15 @@
 
 package org.springframework.util;
 
+import org.jspecify.annotations.Nullable;
+
 /**
  * Exception thrown from {@link MimeTypeUtils#parseMimeType(String)} in case of
  * encountering an invalid content type specification String.
  *
  * @author Juergen Hoeller
  * @author Rossen Stoyanchev
+ * @author Sebastien Deleuze
  * @since 4.0
  */
 @SuppressWarnings("serial")
@@ -35,8 +38,10 @@ public class InvalidMimeTypeException extends IllegalArgumentException {
 	 * @param mimeType the offending media type
 	 * @param message a detail message indicating the invalid part
 	 */
-	public InvalidMimeTypeException(String mimeType, String message) {
+	public InvalidMimeTypeException(String mimeType, @Nullable String message) {
-		super("Invalid mime type \"" + mimeType + "\": " + message);
+		super(message == null ?
+				"Invalid mime type \"" + mimeType + "\"" :
+				"Invalid mime type \"" + mimeType + "\": " + message);
 		this.mimeType = mimeType;
 	}
 

spring-core/src/main/java/org/springframework/util/MimeTypeUtils.java

@@ -203,7 +203,6 @@ public abstract class MimeTypeUtils {
 		return cachedMimeTypes.get(mimeType);
 	}
 
-	@SuppressWarnings("NullAway")
 	private static MimeType parseMimeTypeInternal(String mimeType) {
 		int index = mimeType.indexOf(';');
 		String fullType = (index >= 0 ? mimeType.substring(0, index) : mimeType).trim();

spring-core/src/main/java/org/springframework/util/NumberUtils.java

@@ -236,7 +236,7 @@ public abstract class NumberUtils {
 	 * @see #convertNumberToTargetClass
 	 * @see #parseNumber(String, Class)
 	 */
-	@SuppressWarnings("NullAway")
+	@SuppressWarnings("NullAway") // Dataflow analysis limitation
 	public static <T extends Number> T parseNumber(
 			String text, Class<T> targetClass, @Nullable NumberFormat numberFormat) {