Meta-@Conditional lookup does not work consistently with ASM [SPR-14257]

[spring-projects-issues]

Andy Wilkinson opened SPR-14257 and commented

When ConditionEvaluator looks for Conditional annotations, it doesn't find them when they are a meta-meta-annotation. The problem appears to be due to ConditionEvaluator's use of AnnotationTypeMetadata.getAllAnnotationAttributes which doesn't return all of the values for all of the Conditional annotations that are present. The attached class should hopefully illustrate the behaviour that we're seeing. When run it should output:

com.example.ConditionComposition$MetaFooAndBarConfiguration [class com.example.ConditionComposition$ConditionalOnBar$BarEnabledCondition]
com.example.ConditionComposition$MetaFooAndMetaBarConfiguration []
com.example.ConditionComposition$ExplicitAnnotationConfiguration [class com.example.ConditionComposition$ConditionalOnFoo$FooEnabledCondition, class com.example.ConditionComposition$ConditionalOnBar$BarEnabledCondition]

My expectation is that all three configuration classes should produce the output that ExplicitAnnotationConfiguration produces.

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Affects: 4.2.6

Attachments:

• ConditionComposition.java (3.04 kB)

Issue Links:

• ClassPathScanningCandidateComponentProvider.findCandidateComponents fails on private meta-attributes [SPR-11091] #15717 ClassPathScanningCandidateComponentProvider.findCandidateComponents fails on private meta-attributes
• AnnotationAttributesReadingVisitor.doVisitEnd doesn't handle possible null return from AnnotationUtils.getAnnotations [SPR-12493] #17099 AnnotationAttributesReadingVisitor.doVisitEnd doesn't handle possible null return from AnnotationUtils.getAnnotations

Referenced from: commits 24f5f36, 7de2976

Backported to: 4.2.7

[spring-projects-issues]

Juergen Hoeller commented

This seems to be an inconsistency between reflection-based and ASM-based lookup: with the latter, AnnotationMetadataReadingVisitor seems to be limited to one meta-annotation level in terms of attribute retrieval. We need to allow for attribute lookups across arbitrary meta-annotation levels there, just like StandardAnnotationMetadata does.

[spring-projects-issues]

Juergen Hoeller commented

I've addressed two related issues:

ASM's meta-annotation scanning was tracking visited annotations by annotation type name, therefore not reliably detecting multiple occurences of the same annotation.

Also, we did not traverse to meta-meta-annotations for non-public meta annotations due to fear of illegal access exceptions. This seems to primarily affect attribute retrieval though, not meta-annotation introspection. To be on the safe side, we're guarding against introspection failures through a catch block now.