Revise configuration code for better Spring Native support

[artembilan]

See more info in Spring Native.

At the moment it is important to revise ImportSelector impls and class presence checks.

Related to: spring-projects/spring-framework#18353

[artembilan]

        at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:83) ~[na:na]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:1308) ~[na:na]
        ... 17 common frames omitted
Caused by: java.lang.NoSuchMethodException: org.springframework.integration.config.IntegrationConfigurationBeanFactoryPostProcessor.<init>()

Looks like Spring requires explicit public default ctor for that type of beans in Native mode:

		if (NativeDetector.inNativeImage()) {
			this.instantiationStrategy = new SimpleInstantiationStrategy();
		}
		else {
			this.instantiationStrategy = new CglibSubclassingInstantiationStrategy();
		}

[artembilan]

Another more obvious reflection problem:

Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.integration.config.SourcePollingChannelAdapterFactoryBean]: No default constructor found; nested exception is java.lang.NoSuchMethodException: org.springframework.integration.config.SourcePollingChannelAd
apterFactoryBean.<init>()
        at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:154) ~[na:na]
        at org.springframework.integration.dsl.EndpointSpec.<init>(EndpointSpec.java:60) ~[na:na]
        at org.springframework.integration.dsl.SourcePollingChannelAdapterSpec.<init>(SourcePollingChannelAdapterSpec.java:32) ~[na:na]
        at org.springframework.integration.dsl.IntegrationFlows.from(IntegrationFlows.java:203) ~[na:na]
        at org.springframework.integration.dsl.IntegrationFlows.from(IntegrationFlows.java:195) ~[na:na]
        at org.springframework.integration.dsl.IntegrationFlows.fromSupplier(IntegrationFlows.java:166) ~[na:na]
        at org.springframework.integration.demonative.DemoNativeApplication.printSecondsFlow(DemoNativeApplication.java:20) ~[org.springframework.integration.demonative.DemoNativeApplication:na]
        at java.lang.reflect.Method.invoke(Method.java:566) ~[na:na]
        at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:154) ~[na:na]
        ... 19 common frames omitted
Caused by: java.lang.NoSuchMethodException: org.springframework.integration.config.SourcePollingChannelAdapterFactoryBean.<init>()
        at java.lang.Class.getConstructor0(DynamicHub.java:3349) ~[na:na]
        at java.lang.Class.getDeclaredConstructor(DynamicHub.java:2553) ~[na:na]
        at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:147) ~[na:na]

where the code is like this:

protected EndpointSpec(H handler) {
	Class<?> fClass = ResolvableType.forClass(this.getClass()).as(EndpointSpec.class).resolveGenerics()[1];
	this.endpointFactoryBean = (F) BeanUtils.instantiateClass(fClass);
	this.handler = handler;
}

so, need to figure out how to avoid reflection over there or find out the way to teach it to work with Native image...

[garyrussell]

Proper doc link: https://docs.spring.io/spring-native/docs/0.9.0-SNAPSHOT/reference/htmlsingle/#how-to-contribute-design

[artembilan]

Yeah... Better to say this: https://docs.spring.io/spring-native/docs/current-SNAPSHOT/reference/htmlsingle/#how-to-contribute to align with whatever is the latest.

[artembilan]

Reopen: the work is not done yet.

[artembilan]

GroovyScriptExecutingMessageProcessor:

		GroovyObject goo = (GroovyObject) BeanUtils.instantiateClass(this.scriptClass);

MapToObjectTransformer:

Object target = (this.targetClass != null)
				? BeanUtils.instantiateClass(this.targetClass)
				: this.getBeanFactory().getBean(this.targetBeanName);

Or even JmsChannelFactoryBean:

AbstractMessageListenerContainer container = BeanUtils.instantiateClass(this.containerType);

and respective Java DSL:

protected JmsListenerContainerSpec(Class<C> aClass) {
		super(BeanUtils.instantiateClass(aClass));

Well, technically every single place where we indeed rely on the reflection at runtime.
This probably can be handled only via @NativeHint in Spring Native project.

[artembilan]

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'errorChannel': Unexpected exception during bean creation; nested exception is org.springframework.beans.factory.BeanExpressionException: Expression parsing failed; nested exception is org.springframework.expression.spel.Spel
EvaluationException: EL1005E: Type cannot be found 'org.springframework.integration.context.IntegrationContextUtils'
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:537) ~[na:na]
        at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:335) ~[na:na]
        at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) ~[na:na]
        at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:333) ~[na:na]
        at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:208) ~[na:na]
        at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:944) ~[na:na]
        at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:918) ~[na:na]
        at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:583) ~[na:na]
        at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:774) ~[org.springframework.integration.demonative.DemoNativeApplication:2.5.0-SNAPSHOT]
        at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:443) ~[org.springframework.integration.demonative.DemoNativeApplication:2.5.0-SNAPSHOT]
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:341) ~[org.springframework.integration.demonative.DemoNativeApplication:2.5.0-SNAPSHOT]
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:1352) ~[org.springframework.integration.demonative.DemoNativeApplication:2.5.0-SNAPSHOT]
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:1341) ~[org.springframework.integration.demonative.DemoNativeApplication:2.5.0-SNAPSHOT]
        at org.springframework.integration.demonative.DemoNativeApplication.main(DemoNativeApplication.java:15) ~[org.springframework.integration.demonative.DemoNativeApplication:na]
Caused by: org.springframework.beans.factory.BeanExpressionException: Expression parsing failed; nested exception is org.springframework.expression.spel.SpelEvaluationException: EL1005E: Type cannot be found 'org.springframework.integration.context.IntegrationContextUtils'
        at org.springframework.context.expression.StandardBeanExpressionResolver.evaluate(StandardBeanExpressionResolver.java:169) ~[na:na]
        at org.springframework.integration.config.DefaultConfiguringBeanFactoryPostProcessor.resolveExpression(DefaultConfiguringBeanFactoryPostProcessor.java:595) ~[na:na]
        at org.springframework.integration.config.DefaultConfiguringBeanFactoryPostProcessor.createErrorChannel(DefaultConfiguringBeanFactoryPostProcessor.java:283) ~[na:na]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.obtainFromSupplier(AbstractAutowireCapableBeanFactory.java:1231) ~[na:na]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1173) ~[na:na]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:564) ~[na:na]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:524) ~[na:na]
        ... 13 common frames omitted
Caused by: org.springframework.expression.spel.SpelEvaluationException: EL1005E: Type cannot be found 'org.springframework.integration.context.IntegrationContextUtils'
        at org.springframework.expression.spel.support.StandardTypeLocator.findType(StandardTypeLocator.java:117) ~[na:na]
        at org.springframework.expression.spel.ExpressionState.findType(ExpressionState.java:155) ~[na:na]
        at org.springframework.expression.spel.ast.TypeReference.getValueInternal(TypeReference.java:69) ~[na:na]
        at org.springframework.expression.spel.ast.CompoundExpression.getValueRef(CompoundExpression.java:55) ~[na:na]
        at org.springframework.expression.spel.ast.CompoundExpression.getValueInternal(CompoundExpression.java:91) ~[na:na]
        at org.springframework.expression.spel.ast.SpelNodeImpl.getValue(SpelNodeImpl.java:112) ~[na:na]
        at org.springframework.expression.spel.standard.SpelExpression.getValue(SpelExpression.java:272) ~[na:na]
        at org.springframework.context.expression.StandardBeanExpressionResolver.evaluate(StandardBeanExpressionResolver.java:166) ~[na:na]
        ... 19 common frames omitted

We probably can figure out something on the framework level how to be with this and similar SpEL expressions we use for out-of-the-box and support components, but it is definitely has to be somehow addressed in the target projects for end-user expressions and their types. Probably the same @NativeHint can help but already in the end-user code...

[artembilan]

I'm moving this issue back to 5.5 with more priority at the moment since there is a demand from the community.

With the latest PR the basic app works well.
We probably need to go over a basic Spring Cloud Stream app with this solution to be sure where we are with the rest of reflection in the framework