Missing resource for Testcontainers

[wyhasany]

What does this PR do?

Testcontainers uses ResourceReaper.class as a resource. When I run testcontainers with GraalVM I get following exception:

Caused by: java.lang.IllegalArgumentException: Resource with path 
org/testcontainers/utility/ResourceReaper.class 
could not be found on any of these classloaders: 
[jdk.internal.loader.ClassLoaders$AppClassLoader@2f7c7260]
  org.testcontainers.utility.MountableFile.getClasspathResource(MountableFile.java:158)
  org.testcontainers.utility.MountableFile.forClasspathResource(MountableFile.java:103)
  org.testcontainers.utility.MountableFile.forClasspathResource(MountableFile.java:72)
  org.testcontainers.DockerClientFactory.checkMountableFile(DockerClientFactory.java:274)
  org.testcontainers.DockerClientFactory.isFileMountingSupported(DockerClientFactory.java:97)
  [...]

Code sections where the PR accesses files, network, docker or some external service

It starts here:
https://github.com/testcontainers/testcontainers-java/blob/main/core/src/main/java/org/testcontainers/DockerClientFactory.java#L288

Checklist before merging

• I have considered including reachability metadata directly in the library or the framework (see our contributing document)
• I am the original author of all content provided in the pull request, and I did not copy the content from any other source (see the tests section from our contributing document)
• For all tests where I am not the sole author, I have added a comment that proves I may publish them under the specified license (see the tests section from our contributing document)
• I have properly formatted metadata files (see our formatting guide)
• I have added thorough tests (see the tests section from our contributing document)
• I have filled all places where my pull request accesses files, network, docker, or any other external service (see the section above)

[Kehrlann]

Hey @wyhasany !

I've been working in this area a bit. A few questions:

1. Which version of Testcontainers are you using?
2. Would you mind sharing the test that fails? We could add it to the test file.
3. Have you verified that adding this entry in the reflection metadata fixes your test? It is possible that you get more failures when adding this.

The reason I think this may not be enough is that the check leverages this:

        MountableFile mountableFile = MountableFile.forClasspathResource(
            ResourceReaper.class.getName().replace(".", "/") + ".class"
        );

And this is going to bring a few filesystem-related issues. See the discussions here: testcontainers/testcontainers-java#7954