NullPointerException in FunctionContextUtils (2024.0.0)

[marcins89]

When I upgrade spring cloud to 2024.0.0 i get NullPointerException in FunctionContextUtils:120. I figured out that it happen when I create IntegrationFlow bean with input from function and bean create method has parameters.

For example:

@Bean
    public IntegrationFlow addressFlow(AddressDetailsHandler addressDetailsHandler) {
        return IntegrationFlow.from(AddAddressConsumer.class,  gateway -> gateway.beanName(ADD_ADDRESS_BINDER))
                .handle(addressDetailsHandler)
                .get();
    }

produced NPE but when I changed to

@Bean
    public IntegrationFlow addAddressChannelFlow() {
        return IntegrationFlow.from(AddAddressConsumer.class,  gateway -> gateway.beanName(ADD_ADDRESS_BINDER))
            .channel(ADD_ADDRESS_CHANNEL)
            .get();
    }

    @Bean
    public IntegrationFlow addressFlow(AddressDetailsHandler addressDetailsHandler) {
        return IntegrationFlow.from(ADD_ADDRESS_CHANNEL)
                .handle(addressDetailsHandler)
                .get();
    }

it works. Previously I used spring cloud 2023.0.3 and everything was fine.

[olegz]

Can you please provide a sample app that reproduces the issue? I suspect that it may be Spring Integration issue, but want to diagnose it first.

[artembilan]

Please, share at least stack trace for that NPE, so we will be able to track the problem down.

[marcins89]

Here you can find simple spring app with reproduced issue: https://github.com/marcins89/npereproduction

When you run app without any profile then configuration from NotWorkingConfiguration.class will be use and context won't start (issue reproduced). When you set 'working' profile then configuration from WorkingConfiguration.class will be use and context will start (it is my workaround)

[artembilan]

Thank you for the sample.
Was able to run it and the error looks like this:

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'functionBindingRegistrar' defined in class path resource [org/springframework/cloud/stream/function/FunctionConfiguration.class]: Cannot invoke "java.lang.reflect.Method.getGenericReturnType()" because "method" is null
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1812) ~[spring-beans-6.2.3.jar:6.2.3]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:601) ~[spring-beans-6.2.3.jar:6.2.3]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:523) ~[spring-beans-6.2.3.jar:6.2.3]
	at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:339) ~[spring-beans-6.2.3.jar:6.2.3]
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:346) ~[spring-beans-6.2.3.jar:6.2.3]
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:337) ~[spring-beans-6.2.3.jar:6.2.3]
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) ~[spring-beans-6.2.3.jar:6.2.3]
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.instantiateSingleton(DefaultListableBeanFactory.java:1155) ~[spring-beans-6.2.3.jar:6.2.3]
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingleton(DefaultListableBeanFactory.java:1121) ~[spring-beans-6.2.3.jar:6.2.3]
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:1056) ~[spring-beans-6.2.3.jar:6.2.3]
	at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:987) ~[spring-context-6.2.3.jar:6.2.3]
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:627) ~[spring-context-6.2.3.jar:6.2.3]
	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:146) ~[spring-boot-3.4.3.jar:3.4.3]
	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:752) ~[spring-boot-3.4.3.jar:3.4.3]
	at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:439) ~[spring-boot-3.4.3.jar:3.4.3]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:318) ~[spring-boot-3.4.3.jar:3.4.3]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1361) ~[spring-boot-3.4.3.jar:3.4.3]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1350) ~[spring-boot-3.4.3.jar:3.4.3]
	at pl.softipine.npereproduction.NpereproductionApplication.main(NpereproductionApplication.java:10) ~[classes/:na]
Caused by: java.lang.NullPointerException: Cannot invoke "java.lang.reflect.Method.getGenericReturnType()" because "method" is null
	at org.springframework.cloud.function.context.config.FunctionContextUtils.findBeanType(FunctionContextUtils.java:120) ~[spring-cloud-function-context-4.2.0.jar:4.2.0]
	at org.springframework.cloud.function.context.config.FunctionContextUtils.findType(FunctionContextUtils.java:72) ~[spring-cloud-function-context-4.2.0.jar:4.2.0]
	at org.springframework.cloud.function.context.catalog.FunctionTypeUtils.discoverFunctionType(FunctionTypeUtils.java:392) ~[spring-cloud-function-context-4.2.0.jar:4.2.0]
	at org.springframework.cloud.stream.function.FunctionConfiguration$FunctionBindingRegistrar.filterEligibleFunctionDefinitions(FunctionConfiguration.java:1029) ~[spring-cloud-stream-4.2.0.jar:4.2.0]
	at org.springframework.cloud.stream.function.FunctionConfiguration$FunctionBindingRegistrar.afterPropertiesSet(FunctionConfiguration.java:876) ~[spring-cloud-stream-4.2.0.jar:4.2.0]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1859) ~[spring-beans-6.2.3.jar:6.2.3]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1808) ~[spring-beans-6.2.3.jar:6.2.3]

Looks like difference between working and not is here:

@Bean
public IntegrationFlow testIntegrationFLow(
            ExampleTransformer exampleTransformer,
            ExampleHandler exampleHandler) {

while working is without params:

    @Bean
    public IntegrationFlow channelFlow() {

Somehow Class<?>[] params = getParamTypesFromBeanDefinitionFactory(factory, definition); does not return those params for us.
Investigating...

[artembilan]

So, BeanDefinition for that testConsumer is this:

org.springframework.integration.gateway.AnnotationGatewayProxyFactoryBean<pl.softipine.npereproduction.NotWorkingConfiguration$ExamplePayloadMessageConsumer>

which is exactly what we need.

However the logic in the FunctionContextUtils.findType() is this:

	Object source = definition.getSource();

		Type param = null;
		if (source instanceof MethodMetadata) {
			param = findBeanType(definition, ((MethodMetadata) source).getDeclaringClassName(), ((MethodMetadata) source).getMethodName());
		}
		else if (source instanceof Resource) {
			param = registry.getType(actualName);
		}

		if (param == null) {
			param = definition.getResolvableType().getType();
		}

		if (!(param instanceof ParameterizedType) && beanClass != null) {
			return FunctionTypeUtils.discoverFunctionTypeFromClass(beanClass);
		}
		return param;

So, it checks the MethodMetadata from source first.

Indeed in Spring Integration we do this:

	private Object processStandardIntegrationFlow(StandardIntegrationFlow flow, String flowBeanName) { // NOSONAR complexity
		boolean registerBeanDefinitions = this.beanFactory.containsBeanDefinition(flowBeanName);
		if (registerBeanDefinitions) {
			BeanDefinition beanDefinition = this.beanFactory.getBeanDefinition(flowBeanName);
			flow.setComponentSource(beanDefinition.getSource());
			flow.setComponentDescription(beanDefinition.getDescription());
		}
		Object beanSource = flow.getComponentSource();
		String beanDescription = flow.getComponentDescription();

Then we use that beanSource for every single component registration which belong to the IntegationFlow bean definition.
That was done as part of the fix: spring-projects/spring-integration#9450.

Well, what we have done there is logical since it really helps to determine a bean source in the application context.
However I didn't expect that this source metadata would be used to discover bean type.

We will discuss with @olegz internally what and where can be done to solve the problem.

[olegz]

The issue was with us only retrieving parameter types if method in the bean definition was a factory method (e.g., if (root.isFactoryMethod(method))). In reality we really don't care since we know the method name and simply need to retrieve parameters from it. So, a small change solves the issue.

See the following commit for more details