NPE when @ConditionalOnBean is present alongside with the @MessagingGateway

[shyding]

For example:

5.2.x and above

Describe the bug

In Spring Boot application we declare like this:

	@ConditionalOnBean(name = "foo")
	@MessagingGateway
	public interface ConditionalGateway {

		void testGateway(Object payload);

	}

and get an excpetion at start up:

	at com.example.demo.DemoApplication.main(DemoApplication.java:13) [classes/:na]
Caused by: java.lang.IllegalStateException: Error processing condition on com.example.demo.DemoApplication$ConditionalGateway
	at org.springframework.boot.autoconfigure.condition.SpringBootCondition.matches(SpringBootCondition.java:60) ~[spring-boot-autoconfigure-2.3.3.RELEASE.jar:2.3.3.RELEASE]
	at org.springframework.context.annotation.ConditionEvaluator.shouldSkip(ConditionEvaluator.java:108) ~[spring-context-5.2.8.RELEASE.jar:5.2.8.RELEASE]
	at org.springframework.context.annotation.ConditionEvaluator.shouldSkip(ConditionEvaluator.java:90) ~[spring-context-5.2.8.RELEASE.jar:5.2.8.RELEASE]
	at org.springframework.context.annotation.ConditionEvaluator.shouldSkip(ConditionEvaluator.java:71) ~[spring-context-5.2.8.RELEASE.jar:5.2.8.RELEASE]
	at org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider.isConditionMatch(ClassPathScanningCandidateComponentProvider.java:513) ~[spring-context-5.2.8.RELEASE.jar:5.2.8.RELEASE]
	at org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider.isCandidateComponent(ClassPathScanningCandidateComponentProvider.java:496) ~[spring-context-5.2.8.RELEASE.jar:5.2.8.RELEASE]
	at org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider.scanCandidateComponents(ClassPathScanningCandidateComponentProvider.java:430) ~[spring-context-5.2.8.RELEASE.jar:5.2.8.RELEASE]
	... 22 common frames omitted
Caused by: java.lang.NullPointerException: null
	at org.springframework.boot.autoconfigure.condition.OnBeanCondition.containsBean(OnBeanCondition.java:288) ~[spring-boot-autoconfigure-2.3.3.RELEASE.jar:2.3.3.RELEASE]
	at org.springframework.boot.autoconfigure.condition.OnBeanCondition.getMatchingBeans(OnBeanCondition.java:197) ~[spring-boot-autoconfigure-2.3.3.RELEASE.jar:2.3.3.RELEASE]
	at org.springframework.boot.autoconfigure.condition.OnBeanCondition.getMatchOutcome(OnBeanCondition.java:119) ~[spring-boot-autoconfigure-2.3.3.RELEASE.jar:2.3.3.RELEASE]
	at org.springframework.boot.autoconfigure.condition.SpringBootCondition.matches(SpringBootCondition.java:47) ~[spring-boot-autoconfigure-2.3.3.RELEASE.jar:2.3.3.RELEASE]

[artembilan]

Please, start from StackOverflow and share as much info as possible. Some code to reproduce would be very useful.

We don't handle question here on GH and your description doesn't depict the problem.

Thanks for understanding.

[artembilan]

OK. I decided to play with this and realized that issue is like this:

Caused by: java.lang.IllegalStateException: Error processing condition on com.example.demo.DemoApplication$ConditionalGateway
	at org.springframework.boot.autoconfigure.condition.SpringBootCondition.matches(SpringBootCondition.java:60) ~[spring-boot-autoconfigure-2.3.3.RELEASE.jar:2.3.3.RELEASE]
	at org.springframework.context.annotation.ConditionEvaluator.shouldSkip(ConditionEvaluator.java:108) ~[spring-context-5.2.8.RELEASE.jar:5.2.8.RELEASE]
	at org.springframework.context.annotation.ConditionEvaluator.shouldSkip(ConditionEvaluator.java:90) ~[spring-context-5.2.8.RELEASE.jar:5.2.8.RELEASE]
	at org.springframework.context.annotation.ConditionEvaluator.shouldSkip(ConditionEvaluator.java:71) ~[spring-context-5.2.8.RELEASE.jar:5.2.8.RELEASE]
	at org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider.isConditionMatch(ClassPathScanningCandidateComponentProvider.java:513) ~[spring-context-5.2.8.RELEASE.jar:5.2.8.RELEASE]
	at org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider.isCandidateComponent(ClassPathScanningCandidateComponentProvider.java:496) ~[spring-context-5.2.8.RELEASE.jar:5.2.8.RELEASE]
	at org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider.scanCandidateComponents(ClassPathScanningCandidateComponentProvider.java:430) ~[spring-context-5.2.8.RELEASE.jar:5.2.8.RELEASE]
	... 22 common frames omitted
Caused by: java.lang.NullPointerException: null
	at org.springframework.boot.autoconfigure.condition.OnBeanCondition.containsBean(OnBeanCondition.java:288) ~[spring-boot-autoconfigure-2.3.3.RELEASE.jar:2.3.3.RELEASE]
	at org.springframework.boot.autoconfigure.condition.OnBeanCondition.getMatchingBeans(OnBeanCondition.java:197) ~[spring-boot-autoconfigure-2.3.3.RELEASE.jar:2.3.3.RELEASE]
	at org.springframework.boot.autoconfigure.condition.OnBeanCondition.getMatchOutcome(OnBeanCondition.java:119) ~[spring-boot-autoconfigure-2.3.3.RELEASE.jar:2.3.3.RELEASE]
	at org.springframework.boot.autoconfigure.condition.SpringBootCondition.matches(SpringBootCondition.java:47) ~[spring-boot-autoconfigure-2.3.3.RELEASE.jar:2.3.3.RELEASE]

So, the @ConditionalOnBean indeed doesn't work with the @MessagingGateway...