Introduce "unsafeAllocated" flag in TypeHint

This metadata information is required for supporting libraries using
`sun.misc.Unsafe#allocateInstance(Class<?>)`, even though Spring
Framework is not using this feature.

Closes gh-34055

Author: bclozel

spring-core/src/main/java/org/springframework/aot/hint/MemberCategory.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 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.
@@ -124,6 +124,14 @@ public enum MemberCategory {
 	 * reflection for inner classes but rather makes sure they are available
 	 * via a call to {@link Class#getDeclaredClasses}.
 	 */
-	DECLARED_CLASSES
+	DECLARED_CLASSES,
+
+	/**
+	 * A category that represents the need for
+	 * {@link sun.misc.Unsafe#allocateInstance(Class) unsafe allocation}
+	 * for this type.
+	 * @since 6.2.1
+	 */
+	UNSAFE_ALLOCATED
 
 }

spring-core/src/main/java/org/springframework/aot/nativex/ReflectionHintsWriter.java

@@ -124,6 +124,7 @@ private void handleCategories(Map<String, Object> attributes, Set<MemberCategory
 								attributes.put("allDeclaredMethods", true);
 						case PUBLIC_CLASSES -> attributes.put("allPublicClasses", true);
 						case DECLARED_CLASSES -> attributes.put("allDeclaredClasses", true);
+						case UNSAFE_ALLOCATED -> attributes.put("unsafeAllocated", true);
 					}
 				}
 		);

spring-core/src/test/java/org/springframework/aot/nativex/ReflectionHintsWriterTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 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.
@@ -59,7 +59,7 @@ void one() throws JSONException {
 						MemberCategory.INVOKE_PUBLIC_CONSTRUCTORS, MemberCategory.INVOKE_DECLARED_CONSTRUCTORS,
 						MemberCategory.INTROSPECT_PUBLIC_METHODS, MemberCategory.INTROSPECT_DECLARED_METHODS,
 						MemberCategory.INVOKE_PUBLIC_METHODS, MemberCategory.INVOKE_DECLARED_METHODS,
-						MemberCategory.PUBLIC_CLASSES, MemberCategory.DECLARED_CLASSES)
+						MemberCategory.PUBLIC_CLASSES, MemberCategory.DECLARED_CLASSES, MemberCategory.UNSAFE_ALLOCATED)
 				.withField("DEFAULT_CHARSET")
 				.withField("defaultCharset")
 				.withField("aScore")
@@ -83,6 +83,7 @@ void one() throws JSONException {
 						"allDeclaredMethods": true,
 						"allPublicClasses": true,
 						"allDeclaredClasses": true,
+						"unsafeAllocated": true,
 						"fields": [
 							{ "name": "aScore" },
 							{ "name": "DEFAULT_CHARSET" },