Avoid NPE in case of @lazy @Autowired(required=false)

Issue: SPR-13967

Author: jhoeller

spring-context/src/main/java/org/springframework/context/annotation/ContextAnnotationAutowireCandidateResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 the original author or authors.
+ * Copyright 2002-2016 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.
@@ -21,6 +21,7 @@
 
 import org.springframework.aop.TargetSource;
 import org.springframework.aop.framework.ProxyFactory;
+import org.springframework.beans.factory.NoSuchBeanDefinitionException;
 import org.springframework.beans.factory.annotation.QualifierAnnotationAutowireCandidateResolver;
 import org.springframework.beans.factory.config.DependencyDescriptor;
 import org.springframework.beans.factory.support.DefaultListableBeanFactory;
@@ -79,7 +80,12 @@ public boolean isStatic() {
 			}
 			@Override
 			public Object getTarget() {
-				return beanFactory.doResolveDependency(descriptor, beanName, null, null);
+				Object target = beanFactory.doResolveDependency(descriptor, beanName, null, null);
+				if (target == null) {
+					throw new NoSuchBeanDefinitionException(descriptor.getDependencyType(),
+							"Optional dependency not present for lazy injection point");
+				}
+				return target;
 			}
 			@Override
 			public void releaseTarget(Object target) {

spring-context/src/test/java/org/springframework/context/annotation/LazyAutowiredAnnotationBeanPostProcessorTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 the original author or authors.
+ * Copyright 2002-2016 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.
@@ -118,6 +118,28 @@ public void testLazyResourceInjectionWithNonExistingTarget() {
 		}
 	}
 
+	@Test
+	public void testLazyOptionalResourceInjectionWithNonExistingTarget() {
+		DefaultListableBeanFactory bf = new DefaultListableBeanFactory();
+		bf.setAutowireCandidateResolver(new ContextAnnotationAutowireCandidateResolver());
+		AutowiredAnnotationBeanPostProcessor bpp = new AutowiredAnnotationBeanPostProcessor();
+		bpp.setBeanFactory(bf);
+		bf.addBeanPostProcessor(bpp);
+		RootBeanDefinition bd = new RootBeanDefinition(OptionalFieldResourceInjectionBean.class);
+		bd.setScope(RootBeanDefinition.SCOPE_PROTOTYPE);
+		bf.registerBeanDefinition("annotatedBean", bd);
+
+		OptionalFieldResourceInjectionBean bean = (OptionalFieldResourceInjectionBean) bf.getBean("annotatedBean");
+		assertNotNull(bean.getTestBean());
+		try {
+			bean.getTestBean().getName();
+			fail("Should have thrown NoSuchBeanDefinitionException");
+		}
+		catch (NoSuchBeanDefinitionException ex) {
+			// expected;
+		}
+	}
+
 
 	public interface TestBeanHolder {
 
@@ -136,6 +158,17 @@ public TestBean getTestBean() {
 	}
 
 
+	public static class OptionalFieldResourceInjectionBean implements TestBeanHolder {
+
+		@Autowired(required = false) @Lazy
+		private TestBean testBean;
+
+		public TestBean getTestBean() {
+			return this.testBean;
+		}
+	}
+
+
 	public static class FieldResourceInjectionBeanWithCompositeAnnotation implements TestBeanHolder {
 
 		@LazyInject