Fix potential NPE in ClassPathElement.getResources

[jamesnetherton]

Fixes an issue observed on the Camel Quarkus nightly build with Quarkus 999-SNAPSHOT.

The following change causes the camel-quarkus-kotlin-dsl tests to fail:

9daa467

Caused by: java.lang.NullPointerException
	at java.base/java.util.Objects.requireNonNull(Objects.java:233)
	at java.base/java.util.ImmutableCollections$List12.<init>(ImmutableCollections.java:563)
	at java.base/java.util.List.of(List.java:937)
	at io.quarkus.bootstrap.classloading.ClassPathElement.getResources(ClassPathElement.java:147)
	at io.quarkus.bootstrap.classloading.QuarkusClassLoader.getResources(QuarkusClassLoader.java:270)
	at io.quarkus.bootstrap.classloading.QuarkusClassLoader.getResources(QuarkusClassLoader.java:210)
	at kotlin.script.experimental.jvm.util.JvmClasspathUtilKt.rawClassPathFromKeyResourcePath(jvmClasspathUtil.kt:139)
	at kotlin.script.experimental.jvm.util.JvmClasspathUtilKt.classPathFromTypicalResourceUrls(jvmClasspathUtil.kt:152)
	at kotlin.script.experimental.jvm.util.JvmClasspathUtilKt$classpathFromClassloader$1.invoke(jvmClasspathUtil.kt:96)
	at kotlin.script.experimental.jvm.util.JvmClasspathUtilKt$classpathFromClassloader$1.invoke(jvmClasspathUtil.kt:77)

I'm no expert in this area but the change was enough to get the tests passing again.

[Sanne]

It's good in principle but I'd patch the case of List<ClassPathResource> getResources to be a bit safer, if you don't mind?

(see comments)

Thanks!

[Sanne]

Right I think this is necessary. We might want to clarify the javadoc on getResource: I see many other uses are implementing the nullcheck, so they expect it, but the contract could be clarified.

[Sanne]

In this case while the fix is probably fine, it would be better to track down which implementations of List<ClassPathResource> getResources(String name) actually return null, and have them return an empty list.

I see the implementation in PathTreeClassPathElement does that - wouldn't you rather patch the implementation?

It feels wrong to me in this case as it could more safely return an empty list.

[quarkus-bot]

Status for workflow Quarkus CI

This is the status report for running Quarkus CI on commit 910b9c3.

✅ The latest workflow run for the pull request has completed successfully.

It should be safe to merge provided you have a look at the other checks in the summary.

You can consult the Develocity build scans.

[jamesnetherton]

On reflection, I think I'd prefer to leave this one to the experts. I'll open an issue.

Edit - here's the issue #40438.

[Sanne]

On reflection, I think I'd prefer to leave this one to the experts. I'll open an issue.

Edit - here's the issue #40438.

@jamesnetherton you were so close! Are you sure you don't want to give it a shot?