Spring java.time.ZoneRegion - illegal reflective access operation

Affects: spring-boot-starter-parent 2.5.4 / spring-core 5.3.9

Java $ java -version java version "11.0.12" 2021-07-20 LTS Java(TM) SE Runtime Environment 18.9 (build 11.0.12+8-LTS-237) Java HotSpot(TM) 64-Bit Server VM 18.9 (build 11.0.12+8-LTS-237, mixed mode)

OS Edition: Windows 10 Pro Version: 21H1 Installed on: ‎2020-‎08-‎13 OS build: 19043.1237 Experience: Windows Feature Experience Pack 120.2212.3530.0

WARNING: Illegal reflective access by org.springframework.util.ReflectionUtils (file:.m2/repository/org/springframework/spring-core/5.3.9/spring-core-5.3.9.jar) to method java.time.ZoneRegion.getId()
    at org.springframework.util.ReflectionUtils.makeAccessible(ReflectionUtils.java:573)
    at org.springframework.expression.spel.support.ReflectivePropertyAccessor$OptimalPropertyAccessor.read(ReflectivePropertyAccessor.java:703)
    at org.springframework.expression.spel.ast.PropertyOrFieldReference.readProperty(PropertyOrFieldReference.java:204)
    at org.springframework.expression.spel.ast.PropertyOrFieldReference.getValueInternal(PropertyOrFieldReference.java:104)
    at org.springframework.expression.spel.ast.PropertyOrFieldReference.access$000(PropertyOrFieldReference.java:51)
    at org.springframework.expression.spel.ast.PropertyOrFieldReference$AccessorLValue.getValue(PropertyOrFieldReference.java:406)
    at org.springframework.expression.spel.ast.CompoundExpression.getValueInternal(CompoundExpression.java:92)
    at org.springframework.expression.spel.ast.OpEQ.getValueInternal(OpEQ.java:43)
    at org.springframework.expression.spel.ast.OpEQ.getValueInternal(OpEQ.java:32)
    at org.springframework.expression.spel.ast.SpelNodeImpl.getValue(SpelNodeImpl.java:112)
    at org.springframework.expression.spel.standard.SpelExpression.getValue(SpelExpression.java:337)
    at org.thymeleaf.spring5.expression.SPELVariableExpressionEvaluator.evaluate(SPELVariableExpressionEvaluator.java:265)
    at org.thymeleaf.standard.expression.VariableExpression.executeVariableExpression(VariableExpression.java:166)
    at org.thymeleaf.standard.expression.SimpleExpression.executeSimple(SimpleExpression.java:66)
    at org.thymeleaf.standard.expression.Expression.execute(Expression.java:109)
    at org.thymeleaf.standard.expression.Expression.execute(Expression.java:138)
    at org.thymeleaf.standard.processor.AbstractStandardExpressionAttributeTagProcessor.doProcess(AbstractStandardExpressionAttributeTagProcessor.java:144)
    at org.thymeleaf.processor.element.AbstractAttributeTagProcessor.doProcess(AbstractAttributeTagProcessor.java:74)
    at org.thymeleaf.processor.element.AbstractElementTagProcessor.process(AbstractElementTagProcessor.java:95)
    at org.thymeleaf.util.ProcessorConfigurationUtils$ElementTagProcessorWrapper.process(ProcessorConfigurationUtils.java:633)
    at org.thymeleaf.engine.ProcessorTemplateHandler.handleStandaloneElement(ProcessorTemplateHandler.java:918)
    at org.thymeleaf.engine.StandaloneElementTag.beHandled(StandaloneElementTag.java:228)
    at org.thymeleaf.engine.Model.process(Model.java:282)
    at org.thymeleaf.engine.Model.process(Model.java:290)
    at org.thymeleaf.engine.IteratedGatheringModelProcessable.processIterationModel(IteratedGatheringModelProcessable.java:367)
    at org.thymeleaf.engine.IteratedGatheringModelProcessable.process(IteratedGatheringModelProcessable.java:221)
    at org.thymeleaf.engine.ProcessorTemplateHandler.handleStandaloneElement(ProcessorTemplateHandler.java:942)
    at org.thymeleaf.engine.StandaloneElementTag.beHandled(StandaloneElementTag.java:228)
    at org.thymeleaf.engine.Model.process(Model.java:282)
    at org.thymeleaf.engine.ProcessorTemplateHandler.handleOpenElement(ProcessorTemplateHandler.java:1587)
    at org.thymeleaf.engine.TemplateHandlerAdapterMarkupHandler.handleOpenElementEnd(TemplateHandlerAdapterMarkupHandler.java:304)
    at org.thymeleaf.templateparser.markup.InlinedOutputExpressionMarkupHandler$InlineMarkupAdapterPreProcessorHandler.handleOpenElementEnd(InlinedOutputExpressionMarkupHandler.java:278)

Comment From: jhoeller

It looks like some expression in a Thymeleaf template dereferences a private field on java.time.ZoneRegion, possibly against some domain model object. Please double-check your Thymeleaf files; this needs to be fixed at the user template level. Try to refer to public access methods over field names wherever possible in your SpEL expressions.

Please note that Spring does not generally prevent illegal reflective access. While it doesn't use illegal reflection by default, an application may always ask for a reflective operation that turns into an illegal access warning in your JVM runtime environment. In any case, this does not indicate a SpEL bug, so I'm closing this issue for the time being.