Annotation NPE

[pmsgd]

Hello, I encountered NPE in byte buddy annotation parsing. We use kotlin 1.5.32, mockk library 1.12.3, byte buddy 1.10.22 and for simple mock:

val relNode = mockk<RelNode>()

I get this exception (root cause part only):

Caused by: java.lang.NullPointerException at net.bytebuddy.description.annotation.AnnotationDescription$ForLoadedAnnotation.(AnnotationDescription.java:511) at net.bytebuddy.description.annotation.AnnotationDescription$ForLoadedAnnotation.of(AnnotationDescription.java:534) at net.bytebuddy.description.annotation.AnnotationList$ForLoadedAnnotations.get(AnnotationList.java:235) at net.bytebuddy.description.annotation.AnnotationList$ForLoadedAnnotations.get(AnnotationList.java:192) at java.base/java.util.AbstractList$Itr.next(AbstractList.java:371) at net.bytebuddy.implementation.attribute.AnnotationAppender$ForTypeAnnotations.ofTypeVariable(AnnotationAppender.java:629) at net.bytebuddy.implementation.attribute.AnnotationAppender$ForTypeAnnotations.ofTypeVariable(AnnotationAppender.java:601) at net.bytebuddy.implementation.attribute.MethodAttributeAppender$ForInstrumentedMethod.apply(MethodAttributeAppender.java:198) at net.bytebuddy.implementation.attribute.MethodAttributeAppender$Compound.apply(MethodAttributeAppender.java:484) at net.bytebuddy.dynamic.scaffold.TypeWriter$MethodPool$Record$ForDefinedMethod$WithBody.applyAttributes(TypeWriter.java:701) at net.bytebuddy.dynamic.scaffold.TypeWriter$MethodPool$Record$ForDefinedMethod$WithBody.applyBody(TypeWriter.java:691) at net.bytebuddy.dynamic.scaffold.TypeWriter$MethodPool$Record$ForDefinedMethod.apply(TypeWriter.java:600) at net.bytebuddy.dynamic.scaffold.TypeWriter$Default$ForCreation.create(TypeWriter.java:5751) at net.bytebuddy.dynamic.scaffold.TypeWriter$Default.make(TypeWriter.java:2166) at net.bytebuddy.dynamic.scaffold.subclass.SubclassDynamicTypeBuilder.make(SubclassDynamicTypeBuilder.java:232) at net.bytebuddy.dynamic.scaffold.subclass.SubclassDynamicTypeBuilder.make(SubclassDynamicTypeBuilder.java:204) at net.bytebuddy.dynamic.DynamicType$Builder$AbstractBase.make(DynamicType.java:3659) at net.bytebuddy.dynamic.DynamicType$Builder$AbstractBase$Delegator.make(DynamicType.java:3897) at io.mockk.proxy.jvm.transformation.SubclassInstrumentation.doInterceptedSubclassing(SubclassInstrumentation.kt:83)

Debugged into code it crashes because typeVriable.getDeclaredAnnotations() returns array with single null element. This is caused by metadata method declaration in Apache Calcite library (version 1.30.0) in interface RelNode:

<@Nullable M extends @Nullable Metadata> M metadata(Class<M> metadataClass, RelMetadataQuery mq);

If I create extending interface with method (in Kotlin):

fun metadata(metadataClass: Class<Any?>?, mq: RelMetadataQuery?): Any?

and use it everywhere in unit tests then everything is ok.

[raphw]

Is this also happening with a more recent version of Byte Buddy? If you only update Byte Buddy, its API should be compatible.

[pmsgd]

Yes, byte buddy version 1.12.9 throws the same exception only with different line:

Caused by: java.lang.NullPointerException at net.bytebuddy.description.annotation.AnnotationDescription$ForLoadedAnnotation.(AnnotationDescription.java:657) at net.bytebuddy.description.annotation.AnnotationDescription$ForLoadedAnnotation.of(AnnotationDescription.java:692) at net.bytebuddy.description.annotation.AnnotationList$ForLoadedAnnotations.get(AnnotationList.java:240) at net.bytebuddy.description.annotation.AnnotationList$ForLoadedAnnotations.get(AnnotationList.java:197) at java.base/java.util.AbstractList$Itr.next(AbstractList.java:371) at net.bytebuddy.implementation.attribute.AnnotationAppender$ForTypeAnnotations.ofTypeVariable(AnnotationAppender.java:645) at net.bytebuddy.implementation.attribute.AnnotationAppender$ForTypeAnnotations.ofTypeVariable(AnnotationAppender.java:617) at net.bytebuddy.implementation.attribute.MethodAttributeAppender$ForInstrumentedMethod.apply(MethodAttributeAppender.java:198) at net.bytebuddy.implementation.attribute.MethodAttributeAppender$Compound.apply(MethodAttributeAppender.java:484) at net.bytebuddy.dynamic.scaffold.TypeWriter$MethodPool$Record$ForDefinedMethod$WithBody.applyAttributes(TypeWriter.java:712) at net.bytebuddy.dynamic.scaffold.TypeWriter$MethodPool$Record$ForDefinedMethod$WithBody.applyBody(TypeWriter.java:702) at net.bytebuddy.dynamic.scaffold.TypeWriter$MethodPool$Record$ForDefinedMethod.apply(TypeWriter.java:611) at net.bytebuddy.dynamic.scaffold.TypeWriter$Default$ForCreation.create(TypeWriter.java:5959) at net.bytebuddy.dynamic.scaffold.TypeWriter$Default.make(TypeWriter.java:2213) at net.bytebuddy.dynamic.scaffold.subclass.SubclassDynamicTypeBuilder.make(SubclassDynamicTypeBuilder.java:232) at net.bytebuddy.dynamic.scaffold.subclass.SubclassDynamicTypeBuilder.make(SubclassDynamicTypeBuilder.java:204) at net.bytebuddy.dynamic.DynamicType$Builder$AbstractBase.make(DynamicType.java:3668) at net.bytebuddy.dynamic.DynamicType$Builder$AbstractBase$Delegator.make(DynamicType.java:3906) at io.mockk.proxy.jvm.transformation.SubclassInstrumentation.doInterceptedSubclassing(SubclassInstrumentation.kt:83)

[raphw]

That's strange. What JVM version are you running? This is not supposed to happen.

[pmsgd]

openjdk version "11.0.14" 2022-01-18 OpenJDK Runtime Environment (build 11.0.14+9-post-Debian-1deb11u1) OpenJDK 64-Bit Server VM (build 11.0.14+9-post-Debian-1deb11u1, mixed mode, sharing)

and

openjdk version "11.0.14.1" 2022-02-08 LTS OpenJDK Runtime Environment Zulu11.54+25-CA (build 11.0.14.1+1-LTS) OpenJDK 64-Bit Server VM Zulu11.54+25-CA (build 11.0.14.1+1-LTS, mixed mode)

I have NPE in both of them.

[raphw]

Do you have a reproducer?

[pmsgd]

I tried extract important part but it worked - it must be influenced by something else in our project. I can't publish it but I'll investigate it further.

[pmsgd]

Finally found it. grpc libraries have checkerframework (checkerframework.org) as their dependency. After exclusion (i.e. exclude group: 'org.checkerframework') everything works without NPE again. You may want investigate it deeper but for my case the problem is solved and you can close this ticket.

[raphw]

Alright, does it work with a recent version of the dependency? This error should really not happen.

[pmsgd]

I can't replicate it with recent versions of bytebuddy and checkerframework, i.e. mocking works as it should.