Null-returning instance supplier resolves to NullBean

Issue: SPR-17057

spring-beans/src/main/java/org/springframework/beans/factory/support/AbstractAutowireCapableBeanFactory.java

@@ -1148,9 +1148,10 @@ public abstract class AbstractAutowireCapableBeanFactory extends AbstractBeanFac
 	 * @see #getObjectForBeanInstance
 	 */
 	protected BeanWrapper obtainFromSupplier(Supplier<?> instanceSupplier, String beanName) {
+		Object instance;
+
 		String outerBean = this.currentlyCreatedBean.get();
 		this.currentlyCreatedBean.set(beanName);
-		Object instance;
 		try {
 			instance = instanceSupplier.get();
 		}
@@ -1162,6 +1163,10 @@ public abstract class AbstractAutowireCapableBeanFactory extends AbstractBeanFac
 				this.currentlyCreatedBean.remove();
 			}
 		}
+
+		if (instance == null) {
+			instance = new NullBean();
+		}
 		BeanWrapper bw = new BeanWrapperImpl(instance);
 		initBeanWrapper(bw);
 		return bw;

spring-context/src/test/java/org/springframework/context/annotation/AnnotationConfigApplicationContextTests.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.
@@ -29,8 +29,9 @@ import org.springframework.context.ApplicationContext;
 import org.springframework.context.annotation6.ComponentForScanning;
 import org.springframework.context.annotation6.ConfigForScanning;
 import org.springframework.context.annotation6.Jsr330NamedForScanning;
+import org.springframework.util.ObjectUtils;
 
-import static java.lang.String.format;
+import static java.lang.String.*;
 import static org.hamcrest.Matchers.*;
 import static org.junit.Assert.*;
 import static org.springframework.util.StringUtils.*;
@@ -210,6 +211,22 @@ public class AnnotationConfigApplicationContextTests {
 		assertSame(context, context.getBean("b", BeanB.class).applicationContext);
 	}
 
+	@Test
+	public void individualBeanWithNullReturningSupplier() {
+		AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();
+		context.registerBean("a", BeanA.class, () -> null);
+		context.registerBean("b", BeanB.class, BeanB::new);
+		context.registerBean("c", BeanC.class, BeanC::new);
+		context.refresh();
+
+		assertTrue(ObjectUtils.containsElement(context.getBeanNamesForType(BeanA.class), "a"));
+		assertTrue(ObjectUtils.containsElement(context.getBeanNamesForType(BeanB.class), "b"));
+		assertTrue(ObjectUtils.containsElement(context.getBeanNamesForType(BeanC.class), "c"));
+		assertTrue(context.getBeansOfType(BeanA.class).isEmpty());
+		assertSame(context.getBean(BeanB.class), context.getBeansOfType(BeanB.class).values().iterator().next());
+		assertSame(context.getBean(BeanC.class), context.getBeansOfType(BeanC.class).values().iterator().next());
+	}
+
 	@Test
 	public void individualBeanWithSpecifiedConstructorArguments() {
 		AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();