CastClass exception when wiring Map of beans (NullBean instead of 'null' in the map) [SPR-16033]

[spring-projects-issues]

Francisco Lozano opened SPR-16033 and commented

Offending code has been working since 4.1 at least, up until 5.0.0.RC3. It just started failing in GA.

java.lang.IllegalStateException: Failed to load ApplicationContext
	at org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate.loadContext(DefaultCacheAwareContextLoaderDelegate.java:125)
	at org.springframework.test.context.support.DefaultTestContext.getApplicationContext(DefaultTestContext.java:107)
	at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.injectDependencies(DependencyInjectionTestExecutionListener.java:117)
	at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.prepareTestInstance(DependencyInjectionTestExecutionListener.java:83)
	at org.springframework.test.context.TestContextManager.prepareTestInstance(TestContextManager.java:242)
	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.createTest(SpringJUnit4ClassRunner.java:227)
	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner$1.runReflectiveCall(SpringJUnit4ClassRunner.java:289)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.methodBlock(SpringJUnit4ClassRunner.java:291)
	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:246)
	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:97)
	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
	at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
	at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:27)
	at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:190)
	at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86)
	at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:678)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)
Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'com.mycompany.platform.server.healthcheck.HealthcheckConfiguration': Unsatisfied dependency expressed through field 'healthcheckConfigSets'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'eventListenerAdapterHealthcheckConfigSet' defined in class path resource [com/mycompany/platform/event/provider/EventBusHealthcheckConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.mycompany.common.healthcheck.service.HealthcheckConfigSet]: Factory method 'eventListenerAdapterHealthcheckConfigSet' threw exception; nested exception is java.lang.ClassCastException: org.springframework.beans.factory.support.NullBean cannot be cast to com.mycompany.platform.event.bus.EventListenerAdapter
	at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:581)
	at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:91)
	at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:367)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1340)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:582)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:502)
	at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:312)
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228)
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:310)
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:200)
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:756)
	at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:868)
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:549)
	at org.springframework.test.context.support.AbstractGenericContextLoader.loadContext(AbstractGenericContextLoader.java:128)
	at org.springframework.test.context.support.AbstractGenericContextLoader.loadContext(AbstractGenericContextLoader.java:60)
	at org.springframework.test.context.support.AbstractDelegatingSmartContextLoader.delegateLoading(AbstractDelegatingSmartContextLoader.java:109)
	at org.springframework.test.context.support.AbstractDelegatingSmartContextLoader.loadContext(AbstractDelegatingSmartContextLoader.java:246)
	at org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate.loadContextInternal(DefaultCacheAwareContextLoaderDelegate.java:99)
	at org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate.loadContext(DefaultCacheAwareContextLoaderDelegate.java:117)
	... 26 more
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'eventListenerAdapterHealthcheckConfigSet' defined in class path resource [com/mycompany/platform/event/provider/EventBusHealthcheckConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.mycompany.common.healthcheck.service.HealthcheckConfigSet]: Factory method 'eventListenerAdapterHealthcheckConfigSet' threw exception; nested exception is java.lang.ClassCastException: org.springframework.beans.factory.support.NullBean cannot be cast to com.mycompany.platform.event.bus.EventListenerAdapter
	at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:583)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1249)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1098)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:545)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:502)
	at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:312)
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228)
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:310)
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:200)
	at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:251)
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.addCandidateEntry(DefaultListableBeanFactory.java:1320)
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.findAutowireCandidates(DefaultListableBeanFactory.java:1286)
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveMultipleBeans(DefaultListableBeanFactory.java:1188)
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1091)
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1060)
	at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:578)
	... 44 more
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.mycompany.common.healthcheck.service.HealthcheckConfigSet]: Factory method 'eventListenerAdapterHealthcheckConfigSet' threw exception; nested exception is java.lang.ClassCastException: org.springframework.beans.factory.support.NullBean cannot be cast to com.mycompany.platform.event.bus.EventListenerAdapter
	at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:186)
	at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:575)
	... 59 more
Caused by: java.lang.ClassCastException: org.springframework.beans.factory.support.NullBean cannot be cast to com.mycompany.platform.event.bus.EventListenerAdapter
	at com.mycompany.platform.event.provider.EventBusHealthcheckConfiguration.eventListenerAdapterHealthcheckConfigSet(EventBusHealthcheckConfiguration.java:49)
	at com.mycompany.platform.event.provider.EventBusHealthcheckConfiguration$$EnhancerBySpringCGLIB$$a46517a5.CGLIB$eventListenerAdapterHealthcheckConfigSet$1(<generated>)
	at com.mycompany.platform.event.provider.EventBusHealthcheckConfiguration$$EnhancerBySpringCGLIB$$a46517a5$$FastClassBySpringCGLIB$$e3074686.invoke(<generated>)
	at org.springframework.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:228)
	at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:361)
	at com.mycompany.platform.event.provider.EventBusHealthcheckConfiguration$$EnhancerBySpringCGLIB$$a46517a5.eventListenerAdapterHealthcheckConfigSet(<generated>)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:155)
	... 60 more

Offending bean is defined as:

	@Bean
	@Profile("BATCH")
	HealthcheckConfigSet eventListenerAdapterHealthcheckConfigSet(
			@Autowired(required = false) @Lazy Map<String, EventListenerAdapter> eventListenerAdapters) {
		if (eventListenerAdapters == null || eventListenerAdapters.isEmpty()) {
			return null;
		}

		HealthcheckConfigSet set = new HealthcheckConfigSet(HealthcheckGroup.HEALTH);
		for (Entry<String, EventListenerAdapter> a : eventListenerAdapters.entrySet()) {
			if (a.getValue() == null) {
				LOGGER.info("Cannot configure healthcheck for EventListenerAdapter {}: the adapter is null",
						a.getKey());
				continue;
			} else {
				LOGGER.info("Configuring healthcheck for EventListenerAdapter {}", a.getKey());
				Healthcheck hc = new EventListenerAdapterHealthcheck(a.getKey(), a.getValue());
				set.add("event-listener-adapter-" + a.getKey(), hc);
			}

		}
		return set;
	}

From the code, I understand that at some point the Map contained null values, and now it seems the map contains NullBean instances.

---

Affects: 5.0 GA

Issue Links:

• Autowire contract is not honored in cases where FactoryBean or @Bean return null [SPR-15829] #20384 Autowire contract is not honored in cases where FactoryBean or @Bean return null
• BeanNotOfRequiredTypeException (NullBean instead of null) when calling ApplicationContext.getBean(name, type) [SPR-16342] #20889 BeanNotOfRequiredTypeException (NullBean instead of null) when calling ApplicationContext.getBean(name, type)
• BeanDefinitionValidationException when beans are null (NullBean) and initMethod is set [SPR-16063] #20612 BeanDefinitionValidationException when beans are null (NullBean) and initMethod is set
• CastClass exception (NullBean instead of 'null' value) when getting map of beans directly from ApplicationContext [SPR-16163] #20711 CastClass exception (NullBean instead of 'null' value) when getting map of beans directly from ApplicationContext
• null FactoryBean results in BeanCreationException [SPR-16250] #20797 null FactoryBean results in BeanCreationException
• Consistent non-exposure of null beans in the BeanFactory API [SPR-17034] #21572 Consistent non-exposure of null beans in the BeanFactory API

Referenced from: commits c9d3c26

[spring-projects-issues]

Francisco Lozano commented

Fixing temporarily as:

	@Bean
	@Profile("BATCH")
	HealthcheckConfigSet eventListenerAdapterHealthcheckConfigSet(
			@Autowired(required = false) @Lazy Map<String, EventListenerAdapter> eventListenerAdapters) {
		if (eventListenerAdapters == null || eventListenerAdapters.isEmpty()) {
			return null;
		}

		HealthcheckConfigSet set = new HealthcheckConfigSet(HealthcheckGroup.HEALTH);
		for (Entry<String, EventListenerAdapter> a : eventListenerAdapters.entrySet()) {
			String key = a.getKey();
			EventListenerAdapter value;
			// TODO remove this when #20582 is solved
			try {
				value = a.getValue();
			} catch (ClassCastException e) {
				LOGGER.info("Cannot configure healthcheck for EventListenerAdapter " + key, e);
				continue;
			}
			if (value == null) {
				LOGGER.info("Cannot configure healthcheck for EventListenerAdapter {}: the adapter is null", key);
				continue;
			} else {
				LOGGER.info("Configuring healthcheck for EventListenerAdapter {}", key);
				Healthcheck hc = new EventListenerAdapterHealthcheck(key, value);
				set.add("event-listener-adapter-" + key, hc);
			}

		}
		return set;
	}

[spring-projects-issues]

Francisco Lozano commented

Also reproduced somewhere else (in test code) by doing:

Map<String, EventListenerAdapter> beanMap = ctx.getBeansOfType(EventListenerAdapter.class);

com.mycompany.platform.product.server.services.BatchProfileTest > activated FAILED
    org.springframework.beans.factory.BeanNotOfRequiredTypeException: Bean named 'mongoDBIndexerEventListenerAdapter' is expected to be of type 'com.mycompany.platform.event.bus.EventListenerAdapter' but was actually of type 'org.springframework.beans.factory.support.NullBean'
        at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:384)
        at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:205)
        at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeansOfType(DefaultListableBeanFactory.java:515)
        at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeansOfType(DefaultListableBeanFactory.java:504)
        at org.springframework.context.support.AbstractApplicationContext.getBeansOfType(AbstractApplicationContext.java:1192)
        at com.mycompany.platform.product.server.services.BatchProfileTest.activated(BatchProfileTest.java:44)

[spring-projects-issues]

Juergen Hoeller commented

This is indeed a consequence of a recent change where we're never exposing null values as a bean instance internally. For external consumption, we're still exposing those as null, so it seems we missed the Map injection case there...

[spring-projects-issues]

Francisco Lozano commented

One question: if I change the Map<String,TypeOfBean> to Map<String,Optional<TypeOfBean>>, will I get it right? it could mitigate my case in a cleaner way.

[spring-projects-issues]

Juergen Hoeller commented

We don't support nested Optional declarations that way, I'm afraid. The proper fix is on our end, simply resolving null values accordingly, which I have fixed for 5.0.1 now. Please give the upcoming 5.0.1.BUILD-SNAPSHOT a try if you have a chance.

That said, on your end, I avoid null values in your context setup to begin with. I'd rather expose a dummy listener instance (or whatever it is) instead of a null value from your factory method or FactoryBean.getObject() implementation.

[spring-projects-issues]

Francisco Lozano commented

I'm still getting this:

org.springframework.beans.factory.BeanNotOfRequiredTypeException: Bean named 'mongoDBIndexerEventListenerAdapter' is expected to be of type 'com.kii.platform.ufp.event.bus.EventListenerAdapter' but was actually of type 'org.springframework.beans.factory.support.NullBean'
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:384)
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:205)
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeansOfType(DefaultListableBeanFactory.java:515)
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeansOfType(DefaultListableBeanFactory.java:504)
	at org.springframework.context.support.AbstractApplicationContext.getBeansOfType(AbstractApplicationContext.java:1192)
	at com.mycompany.platform.ufp.ufe.server.services.BatchProfileTest.activated(BatchProfileTest.java:44)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
	at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
	at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:27)
	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
	at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86)
	at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:539)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:761)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:461)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:207)

Line 44 is:

		Map<String, EventListenerAdapter> beanMap = ctx.getBeansOfType(EventListenerAdapter.class);

[spring-projects-issues]

Francisco Lozano commented

(Using Spring 5.0.1.RELEASE).

[spring-projects-issues]

Juergen Hoeller commented

Francisco Lozano, could you please create a separate follow-up issue for this specific case? Indeed, getBeansOfType still doesn't leniently handle null instances yet since that 5.0.1 fix just applied to @Autowired resolution... Let's fix this for getBeansOfType as well but ideally under a separate JIRA ticket, then marked for 5.0.2.

[spring-projects-issues]

Francisco Lozano commented

I CANNOT reproduce with very simple code, however:

@Configuration
public class ConfigClass {
	@Bean
	public Dummy bean1() {
		return new Dummy();
	}

	@Bean
	public Dummy bean2() {
		return new Dummy();
	}

	@Bean
	public Dummy bean3() {
		return new Dummy();
	}

	@Bean
	public Object bean4() {
		return null;
	}
}

		try (AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext()) {
			ctx.register(ConfigClass.class);
			ctx.refresh();
			Map<String, Dummy> beans = ctx.getBeansOfType(Dummy.class);
			assertNotNull(beans.get("bean1"));
			assertNotNull(beans.get("bean2"));
			assertNotNull(beans.get("bean3"));
			assertNull(beans.get("bean4"));

		}

[spring-projects-issues]

Juergen Hoeller commented

I've managed to reproduce it next to my @Autowired test case already, and it's also straightforward to fix. It'd be great to have a separate JIRA issue for tracking it though :-)

[spring-projects-issues]

Francisco Lozano commented

spring-attic/spring-framework-issues#173 managed to reproduce too. I'll open a new issue.

[spring-projects-issues]

Juergen Hoeller commented

Yes please. For better or for worse, @Autowired collection resolution and getBeansOfType are separate code paths. So let's keep this issue for the @Autowired fix (5.0.1) and the new issue for the getBeansOfType fix (5.0.2).

[spring-projects-issues]

Francisco Lozano commented

#20711 here it is. Thanks!