Regression: Consumer with abstract base class in conjunction with generics

[profhenry]

There is another regression with consumer (and supplier as well) in case you have an abstract base class in conjunction with generics.

I simplified it and tried to break it down to its root cause.

The following worked fine with Spring Boot 3.5.13 / Spring Cloud 2025.0.1 but is broken in Spring Boot 4.0.5 / Spring Cloud 2025.1.1

public abstract class AbstractConsumer<M> implements Consumer<M> { }

public class MyConsumer<E> extends AbstractConsumer<Message<E>> {

  @Override
  public void accept(Message<E> aMessage) {
    System.out.println("Receiver message with payload: " + aMessage.getPayload().toString());
  }
}

@Bean
MyConsumer<String> consumer() {
  return new MyConsumer<>();
}

You get the following exception at application startup

2026-04-06T22:15:37.239+02:00 ERROR 80834 --- [           main] o.s.boot.SpringApplication               : Application run failed

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'functionBindingRegistrar' defined in class path resource [org/springframework/cloud/stream/function/FunctionConfiguration.class]: Class must not be null
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1817) ~[spring-beans-7.0.6.jar:7.0.6]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:603) ~[spring-beans-7.0.6.jar:7.0.6]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:525) ~[spring-beans-7.0.6.jar:7.0.6]
	at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:333) ~[spring-beans-7.0.6.jar:7.0.6]
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:371) ~[spring-beans-7.0.6.jar:7.0.6]
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:331) ~[spring-beans-7.0.6.jar:7.0.6]
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:196) ~[spring-beans-7.0.6.jar:7.0.6]
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.instantiateSingleton(DefaultListableBeanFactory.java:1218) ~[spring-beans-7.0.6.jar:7.0.6]
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingleton(DefaultListableBeanFactory.java:1184) ~[spring-beans-7.0.6.jar:7.0.6]
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:1121) ~[spring-beans-7.0.6.jar:7.0.6]
	at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:994) ~[spring-context-7.0.6.jar:7.0.6]
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:621) ~[spring-context-7.0.6.jar:7.0.6]
	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:756) ~[spring-boot-4.0.5.jar:4.0.5]
	at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:445) ~[spring-boot-4.0.5.jar:4.0.5]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:321) ~[spring-boot-4.0.5.jar:4.0.5]
	at org.springframework.boot.test.context.SpringBootContextLoader.lambda$loadContext$2(SpringBootContextLoader.java:155) ~[spring-boot-test-4.0.5.jar:4.0.5]
	at org.springframework.util.function.ThrowingSupplier.get(ThrowingSupplier.java:58) ~[spring-core-7.0.6.jar:7.0.6]
	at org.springframework.util.function.ThrowingSupplier.get(ThrowingSupplier.java:46) ~[spring-core-7.0.6.jar:7.0.6]
	at org.springframework.boot.SpringApplication.withHook(SpringApplication.java:1465) ~[spring-boot-4.0.5.jar:4.0.5]
	at org.springframework.boot.test.context.SpringBootContextLoader$ContextLoaderHook.run(SpringBootContextLoader.java:600) ~[spring-boot-test-4.0.5.jar:4.0.5]
	at org.springframework.boot.test.context.SpringBootContextLoader.loadContext(SpringBootContextLoader.java:155) ~[spring-boot-test-4.0.5.jar:4.0.5]
	at org.springframework.boot.test.context.SpringBootContextLoader.loadContext(SpringBootContextLoader.java:114) ~[spring-boot-test-4.0.5.jar:4.0.5]
	at org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate.loadContextInternal(DefaultCacheAwareContextLoaderDelegate.java:247) ~[spring-test-7.0.6.jar:7.0.6]
	at org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate.lambda$loadContext$0(DefaultCacheAwareContextLoaderDelegate.java:167) ~[spring-test-7.0.6.jar:7.0.6]
	at org.springframework.test.context.cache.DefaultContextCache.put(DefaultContextCache.java:214) ~[spring-test-7.0.6.jar:7.0.6]
	at org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate.loadContext(DefaultCacheAwareContextLoaderDelegate.java:160) ~[spring-test-7.0.6.jar:7.0.6]
	at org.springframework.test.context.support.DefaultTestContext.getApplicationContext(DefaultTestContext.java:128) ~[spring-test-7.0.6.jar:7.0.6]
	at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.injectDependencies(DependencyInjectionTestExecutionListener.java:156) ~[spring-test-7.0.6.jar:7.0.6]
	at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.prepareTestInstance(DependencyInjectionTestExecutionListener.java:111) ~[spring-test-7.0.6.jar:7.0.6]
	at org.springframework.test.context.TestContextManager.prepareTestInstance(TestContextManager.java:260) ~[spring-test-7.0.6.jar:7.0.6]
	at org.springframework.test.context.junit.jupiter.SpringExtension.postProcessTestInstance(SpringExtension.java:210) ~[spring-test-7.0.6.jar:7.0.6]
	at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.lambda$invokeTestInstancePostProcessors$1(ClassBasedTestDescriptor.java:423) ~[junit-jupiter-engine-6.0.3.jar:6.0.3]
	at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.executeAndMaskThrowable(ClassBasedTestDescriptor.java:428) ~[junit-jupiter-engine-6.0.3.jar:6.0.3]
	at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.lambda$invokeTestInstancePostProcessors$0(ClassBasedTestDescriptor.java:422) ~[junit-jupiter-engine-6.0.3.jar:6.0.3]
	at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:184) ~[na:na]
	at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:197) ~[na:na]
	at java.base/java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:179) ~[na:na]
	at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:197) ~[na:na]
	at java.base/java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1708) ~[na:na]
	at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:509) ~[na:na]
	at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499) ~[na:na]
	at java.base/java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:151) ~[na:na]
	at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:174) ~[na:na]
	at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) ~[na:na]
	at java.base/java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:596) ~[na:na]
	at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.invokeTestInstancePostProcessors(ClassBasedTestDescriptor.java:422) ~[junit-jupiter-engine-6.0.3.jar:6.0.3]
	at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.lambda$instantiateAndPostProcessTestInstance$0(ClassBasedTestDescriptor.java:334) ~[junit-jupiter-engine-6.0.3.jar:6.0.3]
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:74) ~[junit-platform-engine-6.0.3.jar:6.0.3]
	at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.instantiateAndPostProcessTestInstance(ClassBasedTestDescriptor.java:333) ~[junit-jupiter-engine-6.0.3.jar:6.0.3]
	at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.lambda$testInstancesProvider$1(ClassBasedTestDescriptor.java:322) ~[junit-jupiter-engine-6.0.3.jar:6.0.3]
	at java.base/java.util.Optional.orElseGet(Optional.java:364) ~[na:na]
	at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.lambda$testInstancesProvider$0(ClassBasedTestDescriptor.java:321) ~[junit-jupiter-engine-6.0.3.jar:6.0.3]
	at org.junit.jupiter.engine.execution.TestInstancesProvider.getTestInstances(TestInstancesProvider.java:27) ~[junit-jupiter-engine-6.0.3.jar:6.0.3]
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$prepare$0(TestMethodTestDescriptor.java:127) ~[junit-jupiter-engine-6.0.3.jar:6.0.3]
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:74) ~[junit-platform-engine-6.0.3.jar:6.0.3]
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.prepare(TestMethodTestDescriptor.java:126) ~[junit-jupiter-engine-6.0.3.jar:6.0.3]
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.prepare(TestMethodTestDescriptor.java:70) ~[junit-jupiter-engine-6.0.3.jar:6.0.3]
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$prepare$0(NodeTestTask.java:144) ~[junit-platform-engine-6.0.3.jar:6.0.3]
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:74) ~[junit-platform-engine-6.0.3.jar:6.0.3]
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.prepare(NodeTestTask.java:144) ~[junit-platform-engine-6.0.3.jar:6.0.3]
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:110) ~[junit-platform-engine-6.0.3.jar:6.0.3]
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1596) ~[na:na]
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:42) ~[junit-platform-engine-6.0.3.jar:6.0.3]
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$2(NodeTestTask.java:180) ~[junit-platform-engine-6.0.3.jar:6.0.3]
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:74) ~[junit-platform-engine-6.0.3.jar:6.0.3]
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$1(NodeTestTask.java:166) ~[junit-platform-engine-6.0.3.jar:6.0.3]
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:138) ~[junit-platform-engine-6.0.3.jar:6.0.3]
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$0(NodeTestTask.java:164) ~[junit-platform-engine-6.0.3.jar:6.0.3]
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:74) ~[junit-platform-engine-6.0.3.jar:6.0.3]
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:163) ~[junit-platform-engine-6.0.3.jar:6.0.3]
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:116) ~[junit-platform-engine-6.0.3.jar:6.0.3]
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1596) ~[na:na]
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:42) ~[junit-platform-engine-6.0.3.jar:6.0.3]
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$2(NodeTestTask.java:180) ~[junit-platform-engine-6.0.3.jar:6.0.3]
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:74) ~[junit-platform-engine-6.0.3.jar:6.0.3]
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$1(NodeTestTask.java:166) ~[junit-platform-engine-6.0.3.jar:6.0.3]
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:138) ~[junit-platform-engine-6.0.3.jar:6.0.3]
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$0(NodeTestTask.java:164) ~[junit-platform-engine-6.0.3.jar:6.0.3]
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:74) ~[junit-platform-engine-6.0.3.jar:6.0.3]
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:163) ~[junit-platform-engine-6.0.3.jar:6.0.3]
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:116) ~[junit-platform-engine-6.0.3.jar:6.0.3]
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:36) ~[junit-platform-engine-6.0.3.jar:6.0.3]
	at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:52) ~[junit-platform-engine-6.0.3.jar:6.0.3]
	at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:58) ~[junit-platform-engine-6.0.3.jar:6.0.3]
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.executeEngine(EngineExecutionOrchestrator.java:246) ~[junit-platform-launcher-6.0.3.jar:6.0.3]
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.failOrExecuteEngine(EngineExecutionOrchestrator.java:218) ~[junit-platform-launcher-6.0.3.jar:6.0.3]
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:179) ~[junit-platform-launcher-6.0.3.jar:6.0.3]
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:108) ~[junit-platform-launcher-6.0.3.jar:6.0.3]
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.lambda$execute$0(EngineExecutionOrchestrator.java:66) ~[junit-platform-launcher-6.0.3.jar:6.0.3]
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.withInterceptedStreams(EngineExecutionOrchestrator.java:157) ~[junit-platform-launcher-6.0.3.jar:6.0.3]
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:65) ~[junit-platform-launcher-6.0.3.jar:6.0.3]
	at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:125) ~[junit-platform-launcher-6.0.3.jar:6.0.3]
	at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:114) ~[junit-platform-launcher-6.0.3.jar:6.0.3]
	at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:101) ~[junit-platform-launcher-6.0.3.jar:6.0.3]
	at org.junit.platform.launcher.core.DelegatingLauncher.execute(DelegatingLauncher.java:53) ~[junit-platform-launcher-6.0.3.jar:6.0.3]
	at org.junit.platform.launcher.core.InterceptingLauncher.lambda$execute$1(InterceptingLauncher.java:49) ~[junit-platform-launcher-6.0.3.jar:6.0.3]
	at org.junit.platform.launcher.core.ClasspathAlignmentCheckingLauncherInterceptor.intercept(ClasspathAlignmentCheckingLauncherInterceptor.java:25) ~[junit-platform-launcher-6.0.3.jar:6.0.3]
	at org.junit.platform.launcher.core.InterceptingLauncher.execute(InterceptingLauncher.java:48) ~[junit-platform-launcher-6.0.3.jar:6.0.3]
	at org.junit.platform.launcher.core.DelegatingLauncher.execute(DelegatingLauncher.java:53) ~[junit-platform-launcher-6.0.3.jar:6.0.3]
	at org.junit.platform.launcher.core.SessionPerRequestLauncher.execute(SessionPerRequestLauncher.java:74) ~[junit-platform-launcher-6.0.3.jar:6.0.3]
	at org.eclipse.jdt.internal.junit5.runner.JUnit5TestReference.run(JUnit5TestReference.java:100) ~[.cp/:na]
	at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:40) ~[.cp/:na]
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:520) ~[.cp/:na]
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:748) ~[.cp/:na]
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:443) ~[.cp/:na]
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:211) ~[.cp/:na]
Caused by: java.lang.IllegalArgumentException: Class must not be null
	at org.springframework.util.Assert.notNull(Assert.java:182) ~[spring-core-7.0.6.jar:7.0.6]
	at org.springframework.core.ResolvableType.forClassWithGenerics(ResolvableType.java:1172) ~[spring-core-7.0.6.jar:7.0.6]
	at org.springframework.cloud.function.context.catalog.FunctionTypeUtils.resolveType(FunctionTypeUtils.java:386) ~[spring-cloud-function-context-5.0.1.jar:5.0.1]
	at org.springframework.cloud.function.context.catalog.FunctionTypeUtils.getInputType(FunctionTypeUtils.java:436) ~[spring-cloud-function-context-5.0.1.jar:5.0.1]
	at org.springframework.cloud.function.context.FunctionRegistration.type(FunctionRegistration.java:129) ~[spring-cloud-function-context-5.0.1.jar:5.0.1]
	at org.springframework.cloud.function.context.catalog.BeanFactoryAwareFunctionRegistry.lookup(BeanFactoryAwareFunctionRegistry.java:192) ~[spring-cloud-function-context-5.0.1.jar:5.0.1]
	at org.springframework.cloud.function.context.FunctionCatalog.lookup(FunctionCatalog.java:39) ~[spring-cloud-function-context-5.0.1.jar:5.0.1]
	at org.springframework.cloud.stream.function.FunctionConfiguration$FunctionBindingRegistrar.afterPropertiesSet(FunctionConfiguration.java:890) ~[spring-cloud-stream-5.0.1.jar:5.0.1]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1864) ~[spring-beans-7.0.6.jar:7.0.6]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1813) ~[spring-beans-7.0.6.jar:7.0.6]
	... 105 common frames omitted

This might be a bug in FunctionTypeUtils or Spring Cloud not using FunctionTypeUtils properly.

It might be related to

• Regression: Consumer with generics #1296
• Type resolution with deep generic hierarchies is incorrect  #1312
• UPDATED: Type resolution with deep generic hierarchies still fail in 2025.1.1 (regression from issue #1312) #1325
• Refine ResolvableType type variable resolution spring-projects/spring-framework#33887

[profhenry]

I have added a small sample with a test case, you can find it here.

[profhenry]

It seems that this is resolved with #1333