[Bug]: NullPointerException from ResourceReaper in GenericContainer.stop

[findepi]

Module

Core

Testcontainers version

2.0.3

Using the latest Testcontainers version?

Yes

Host OS

Linux

Host Arch

x86

Docker version

GitHub hosted runners

What happened?

java.lang.NullPointerException: Cannot invoke "Object.hashCode()" because "key" is null
	at java.base/java.util.concurrent.ConcurrentHashMap.replaceNode(ConcurrentHashMap.java:1125)
	at java.base/java.util.concurrent.ConcurrentHashMap.remove(ConcurrentHashMap.java:1116)
	at org.testcontainers.utility.ResourceReaper.stopAndRemoveContainer(ResourceReaper.java:175)
	at org.testcontainers.containers.GenericContainer.stop(GenericContainer.java:652)
	at io.trino.tests.product.launcher.env.DockerContainer.reset(DockerContainer.java:411)
	at io.trino.tests.product.launcher.env.Environment.tryStart(Environment.java:157)

Exact repro steps are unclear.
Based on exceptions logged earlier in the CI run (https://github.com/trinodb/trino/actions/runs/22016571723/job/63619535768?pr=28120) this may be after a failed startup attempt.

Relevant log output

Additional Information

https://github.com/trinodb/trino/actions/runs/22016571723/job/63619535768?pr=28120

[PreAgile]

I took a look at this — the NPE comes from ConcurrentHashMap.remove(null) inside stopAndRemoveContainer(), since ConcurrentHashMap doesn't accept null keys.

One thing I noticed is that GenericContainer.stop() already guards against a null containerId before calling into ResourceReaper, so it's not obvious how null gets through. Could be a race or another caller hitting the deprecated overload.

I'm thinking a simple null check (early return) in both stopAndRemoveContainer() overloads would prevent the crash. The deeper root cause could be investigated separately if needed.

Would that approach work, or would you prefer finding the exact path first?