Java 9: Avoid illegal reflective access warning for SpEL method reference [SPR-16845]

[spring-projects-issues]

Cristian Vasile Mocanu opened SPR-16845 and commented

When running spring under Java 9 (build 9.0.4+11), I get the following in the console (running with --illegal-access=warn):

WARNING: Illegal reflective access by org.springframework.util.ReflectionUtils (file:/home/cvmocanu/.m2/repository/org/springframework/spring-core/5.0.6.RELEASE/spring-core-5.0.6.RELEASE.jar) to method sun.nio.fs.UnixPath.toAbsolutePath()
WARNING: Illegal reflective access by org.springframework.util.ReflectionUtils (file:/home/cvmocanu/.m2/repository/org/springframework/spring-core/5.0.6.RELEASE/spring-core-5.0.6.RELEASE.jar) to method sun.nio.fs.UnixPath.toString()

Running with --illegal-access=debug, reveals the stacktrace:

WARNING: Illegal reflective access by org.springframework.util.ReflectionUtils (file:/home/cvmocanu/.m2/repository/org/springframework/spring-core/5.0.6.RELEASE/spring-core-5.0.6.RELEASE.jar) to method sun.nio.fs.UnixPath.toAbsolutePath()
	at org.springframework.util.ReflectionUtils.makeAccessible(ReflectionUtils.java:472)
	at org.springframework.expression.spel.support.ReflectiveMethodExecutor.execute(ReflectiveMethodExecutor.java:112)
	at org.springframework.expression.spel.ast.MethodReference.getValueInternal(MethodReference.java:129)
	at org.springframework.expression.spel.ast.MethodReference.getValueInternal(MethodReference.java:85)
	at org.springframework.expression.spel.ast.CompoundExpression.getValueRef(CompoundExpression.java:57)
	at org.springframework.expression.spel.ast.CompoundExpression.getValueInternal(CompoundExpression.java:87)
	at org.springframework.expression.spel.ast.SpelNodeImpl.getValue(SpelNodeImpl.java:120)
	at org.springframework.expression.spel.standard.SpelExpression.getValue(SpelExpression.java:242)
	at org.springframework.context.expression.StandardBeanExpressionResolver.evaluate(StandardBeanExpressionResolver.java:161)
	at org.springframework.beans.factory.support.AbstractBeanFactory.evaluateBeanDefinitionString(AbstractBeanFactory.java:1452)
	at org.springframework.beans.factory.support.BeanDefinitionValueResolver.doEvaluate(BeanDefinitionValueResolver.java:266)
	at org.springframework.beans.factory.support.BeanDefinitionValueResolver.evaluate(BeanDefinitionValueResolver.java:223)
	at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveValueIfNecessary(BeanDefinitionValueResolver.java:191)
	at org.springframework.beans.factory.support.ConstructorResolver.resolveConstructorArguments(ConstructorResolver.java:636)
	at org.springframework.beans.factory.support.ConstructorResolver.autowireConstructor(ConstructorResolver.java:148)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireConstructor(AbstractAutowireCapableBeanFactory.java:1274)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1131)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:541)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:501)
	at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveInnerBean(BeanDefinitionValueResolver.java:312)
	at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveValueIfNecessary(BeanDefinitionValueResolver.java:124)
	at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveManagedList(BeanDefinitionValueResolver.java:401)
	at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveValueIfNecessary(BeanDefinitionValueResolver.java:159)
	at org.springframework.beans.factory.support.ConstructorResolver.resolveConstructorArguments(ConstructorResolver.java:636)
	at org.springframework.beans.factory.support.ConstructorResolver.autowireConstructor(ConstructorResolver.java:148)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireConstructor(AbstractAutowireCapableBeanFactory.java:1274)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1131)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:541)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:501)
	at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:317)
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228)
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:315)
WARNING: Illegal reflective access by org.springframework.util.ReflectionUtils (file:/home/cvmocanu/.m2/repository/org/springframework/spring-core/5.0.6.RELEASE/spring-core-5.0.6.RELEASE.jar) to method sun.nio.fs.UnixPath.toString()
	at org.springframework.util.ReflectionUtils.makeAccessible(ReflectionUtils.java:472)
	at org.springframework.expression.spel.support.ReflectiveMethodExecutor.execute(ReflectiveMethodExecutor.java:112)
	at org.springframework.expression.spel.ast.MethodReference.getValueInternal(MethodReference.java:129)
	at org.springframework.expression.spel.ast.MethodReference.access$000(MethodReference.java:49)
	at org.springframework.expression.spel.ast.MethodReference$MethodValueRef.getValue(MethodReference.java:347)
	at org.springframework.expression.spel.ast.CompoundExpression.getValueInternal(CompoundExpression.java:88)
	at org.springframework.expression.spel.ast.SpelNodeImpl.getValue(SpelNodeImpl.java:120)
	at org.springframework.expression.spel.standard.SpelExpression.getValue(SpelExpression.java:242)
	at org.springframework.context.expression.StandardBeanExpressionResolver.evaluate(StandardBeanExpressionResolver.java:161)
	at org.springframework.beans.factory.support.AbstractBeanFactory.evaluateBeanDefinitionString(AbstractBeanFactory.java:1452)
	at org.springframework.beans.factory.support.BeanDefinitionValueResolver.doEvaluate(BeanDefinitionValueResolver.java:266)
	at org.springframework.beans.factory.support.BeanDefinitionValueResolver.evaluate(BeanDefinitionValueResolver.java:223)
	at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveValueIfNecessary(BeanDefinitionValueResolver.java:191)
	at org.springframework.beans.factory.support.ConstructorResolver.resolveConstructorArguments(ConstructorResolver.java:636)
	at org.springframework.beans.factory.support.ConstructorResolver.autowireConstructor(ConstructorResolver.java:148)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireConstructor(AbstractAutowireCapableBeanFactory.java:1274)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1131)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:541)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:501)
	at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveInnerBean(BeanDefinitionValueResolver.java:312)
	at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveValueIfNecessary(BeanDefinitionValueResolver.java:124)
	at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveManagedList(BeanDefinitionValueResolver.java:401)
	at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveValueIfNecessary(BeanDefinitionValueResolver.java:159)
	at org.springframework.beans.factory.support.ConstructorResolver.resolveConstructorArguments(ConstructorResolver.java:636)
	at org.springframework.beans.factory.support.ConstructorResolver.autowireConstructor(ConstructorResolver.java:148)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireConstructor(AbstractAutowireCapableBeanFactory.java:1274)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1131)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:541)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:501)
	at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:317)
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228)
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:315)

The warning comes from this SpEL expression:

<constructor-arg value="#{commandLineArguments.propertiesFilePath.toAbsolutePath().toString()}"/>

where propertiesFilePath is of type java.nio.file.Path.

---

Affects: 5.0.6

[spring-projects-issues]

Cristian Vasile Mocanu commented

Please close this ticket as WONT_FIX if you think it's invalid (and the only solution is for me to add --add-opens).

On the other hand, is there any way that SpEL could be changed so that Java no longer shows this warning? Maybe using java.nio.file.Path (the type of the field) instead of the actual instance.getClass(), when calling class getMethod()?
If not, this seems a design issue of Java 9 modules. It shouldn't be any problem to reflectively call methods exposed through an interface in an exported package. Then again, I just started learning about modules, so I may be misunderstanding some things.

[spring-projects-issues]

Juergen Hoeller commented

As of 5.1, ReflectiveMethodExecutor resolves the given method handle to an interface method for invocation purposes, if possible. This seems to work fine for common cases both within and outside of the module system.

[spring-projects-issues]

Marcel commented

I still get this:
WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by org.springframework.util.ReflectionUtils (file:/some/path/WEB-INF/lib/spring-core-5.1.2.RELEASE.jar) to field java.sql.Timestamp.nanos
WARNING: Please consider reporting this to the maintainers of org.springframework.util.ReflectionUtils
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release

[spring-projects-issues]

Juergen Hoeller commented

L., your particular warning is not related to the ticket here. Some code uses Spring's ReflectionUtils to introspect the nanos field in a java.sql.Timestamp instance; it is not ReflectionUtils itself to blame here but rather whoever calls it (possibly Spring Data, can only really be told through the stacktrace) and therefore to be reported to the originating project.