Properly resolve null beans as getBeansOfType result entries

Issue: SPR-16163

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

@@ -505,6 +505,7 @@ public class DefaultListableBeanFactory extends AbstractAutowireCapableBeanFacto
 	}
 
 	@Override
+	@SuppressWarnings("unchecked")
 	public <T> Map<String, T> getBeansOfType(@Nullable Class<T> type, boolean includeNonSingletons, boolean allowEagerInit)
 			throws BeansException {
 
@@ -512,7 +513,8 @@ public class DefaultListableBeanFactory extends AbstractAutowireCapableBeanFacto
 		Map<String, T> result = new LinkedHashMap<>(beanNames.length);
 		for (String beanName : beanNames) {
 			try {
-				result.put(beanName, getBean(beanName, type));
+				Object beanInstance = getBean(beanName);
+				result.put(beanName, (beanInstance instanceof NullBean ? null : (T) beanInstance));
 			}
 			catch (BeanCreationException ex) {
 				Throwable rootCause = ex.getMostSpecificCause();

spring-beans/src/test/java/org/springframework/beans/factory/annotation/AutowiredAnnotationBeanPostProcessorTests.java

@@ -701,6 +701,11 @@ public class AutowiredAnnotationBeanPostProcessorTests {
 		assertEquals(2, bean.getNestedTestBeans().size());
 		assertNull(bean.getNestedTestBeans().get(0));
 		assertSame(ntb2, bean.getNestedTestBeans().get(1));
+
+		Map<String, NestedTestBean> map = bf.getBeansOfType(NestedTestBean.class);
+		assertNull(map.get("nestedTestBean1"));
+		assertSame(ntb2, map.get("nestedTestBean2"));
+
 		bf.destroySingletons();
 	}