BeanValidationPostProcessor validates singleton target behind proxy

Issue: SPR-17273

spring-context/src/main/java/org/springframework/validation/beanvalidation/BeanValidationPostProcessor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2018 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.
@@ -23,6 +23,7 @@ import javax.validation.Validation;
 import javax.validation.Validator;
 import javax.validation.ValidatorFactory;
 
+import org.springframework.aop.framework.AopProxyUtils;
 import org.springframework.beans.BeansException;
 import org.springframework.beans.factory.BeanInitializationException;
 import org.springframework.beans.factory.InitializingBean;
@@ -107,7 +108,12 @@ public class BeanValidationPostProcessor implements BeanPostProcessor, Initializ
 	 */
 	protected void doValidate(Object bean) {
 		Assert.state(this.validator != null, "No Validator set");
-		Set<ConstraintViolation<Object>> result = this.validator.validate(bean);
+		Object objectToValidate = AopProxyUtils.getSingletonTarget(bean);
+		if (objectToValidate == null) {
+			objectToValidate = bean;
+		}
+		Set<ConstraintViolation<Object>> result = this.validator.validate(objectToValidate);
+
 		if (!result.isEmpty()) {
 			StringBuilder sb = new StringBuilder("Bean state is invalid: ");
 			for (Iterator<ConstraintViolation<Object>> it = result.iterator(); it.hasNext();) {

spring-context/src/test/java/org/springframework/validation/beanvalidation/BeanValidationPostProcessorTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2018 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.
@@ -22,10 +22,13 @@ import javax.validation.constraints.Size;
 
 import org.junit.Test;
 
+import org.springframework.aop.framework.autoproxy.DefaultAdvisorAutoProxyCreator;
 import org.springframework.beans.factory.BeanCreationException;
 import org.springframework.beans.factory.support.RootBeanDefinition;
 import org.springframework.context.annotation.CommonAnnotationBeanPostProcessor;
 import org.springframework.context.support.GenericApplicationContext;
+import org.springframework.scheduling.annotation.Async;
+import org.springframework.scheduling.annotation.AsyncAnnotationAdvisor;
 import org.springframework.tests.sample.beans.TestBean;
 
 import static org.junit.Assert.*;
@@ -76,6 +79,20 @@ public class BeanValidationPostProcessorTests {
 		ac.close();
 	}
 
+	@Test
+	public void testNotNullConstraintAfterInitializationWithProxy() {
+		GenericApplicationContext ac = new GenericApplicationContext();
+		RootBeanDefinition bvpp = new RootBeanDefinition(BeanValidationPostProcessor.class);
+		bvpp.getPropertyValues().add("afterInitialization", true);
+		ac.registerBeanDefinition("bvpp", bvpp);
+		ac.registerBeanDefinition("capp", new RootBeanDefinition(CommonAnnotationBeanPostProcessor.class));
+		ac.registerBeanDefinition("bean", new RootBeanDefinition(AfterInitConstraintBean.class));
+		ac.registerBeanDefinition("autoProxyCreator", new RootBeanDefinition(DefaultAdvisorAutoProxyCreator.class));
+		ac.registerBeanDefinition("asyncAdvisor", new RootBeanDefinition(AsyncAnnotationAdvisor.class));
+		ac.refresh();
+		ac.close();
+	}
+
 	@Test
 	public void testSizeConstraint() {
 		GenericApplicationContext ac = new GenericApplicationContext();
@@ -156,6 +173,10 @@ public class BeanValidationPostProcessorTests {
 		public void init() {
 			this.testBean = new TestBean();
 		}
+
+		@Async
+		void asyncMethod() {
+		}
 	}
 
 }