Refine `@EmbeddableInstantiator` reflection hints

Based on @odrotbohm proposal to manage a wider set
of use cases.

Closes gh-31534

spring-orm/src/main/java/org/springframework/orm/jpa/persistenceunit/PersistenceManagedTypesBeanRegistrationAotProcessor.java

@@ -23,7 +23,6 @@ import javax.lang.model.element.Modifier;
 
 import jakarta.persistence.Convert;
 import jakarta.persistence.Converter;
-import jakarta.persistence.Embedded;
 import jakarta.persistence.EntityListeners;
 import jakarta.persistence.IdClass;
 import jakarta.persistence.PostLoad;
@@ -200,16 +199,22 @@ class PersistenceManagedTypesBeanRegistrationAotProcessor implements BeanRegistr
 				return;
 			}
 			ReflectionHints reflection = hints.reflection();
+			registerInstantiatorForReflection(reflection,
+					AnnotationUtils.findAnnotation(managedClass, embeddableInstantiatorClass));
 			ReflectionUtils.doWithFields(managedClass, field -> {
-				Embedded embeddedAnnotation = AnnotationUtils.findAnnotation(field, Embedded.class);
-				if (embeddedAnnotation != null && field.getAnnotatedType().getType() instanceof Class<?> embeddedClass) {
-						Annotation embeddableInstantiatorAnnotation = AnnotationUtils.findAnnotation(embeddedClass, embeddableInstantiatorClass);
-						if (embeddableInstantiatorAnnotation != null) {
-							Class<?> embeddableInstantiatorClass = (Class<?>) AnnotationUtils.getAnnotationAttributes(embeddableInstantiatorAnnotation).get("value");
-							reflection.registerType(embeddableInstantiatorClass, MemberCategory.INVOKE_DECLARED_CONSTRUCTORS);
+				registerInstantiatorForReflection(reflection,
+						AnnotationUtils.findAnnotation(field, embeddableInstantiatorClass));
+				registerInstantiatorForReflection(reflection,
+						AnnotationUtils.findAnnotation(field.getType(), embeddableInstantiatorClass));
+			});
 		}
+
+		private void registerInstantiatorForReflection(ReflectionHints reflection, @Nullable Annotation annotation) {
+			if (annotation == null) {
+				return;
 			}
-			});
+			Class<?> embeddableInstantiatorClass = (Class<?>) AnnotationUtils.getAnnotationAttributes(annotation).get("value");
+			reflection.registerType(embeddableInstantiatorClass, MemberCategory.INVOKE_DECLARED_CONSTRUCTORS);
 		}
 	}
 }