Refine null-safety in the spring-beans module

See gh-34152

spring-beans/src/main/java/org/springframework/beans/factory/config/FieldRetrievingFactoryBean.java

@@ -158,7 +158,7 @@ public void setBeanClassLoader(ClassLoader classLoader) {
 
 
 	@Override
-	@SuppressWarnings("NullAway")
+	@SuppressWarnings("NullAway") // Lazy initialization
 	public void afterPropertiesSet() throws ClassNotFoundException, NoSuchFieldException {
 		if (this.targetClass != null && this.targetObject != null) {
 			throw new IllegalArgumentException("Specify either targetClass or targetObject, not both");