Blockhound: Allow blocking call in kubernetes-client WatchEventsListener

[sh-cho]

Motivation:
Blockhound detects blocked thread after upgrading kubernetes-client 7.3.1 (#6271, https://github.com/line/armeria/actions/runs/15771639756/job/44457567699)

Modification:

• Remove io.fabric8.kubernetes.client.http.StandardHttpRequest$Builder from allow list, as it uses UUID created via AtomicLong now.
• Add io.fabric8.kubernetes.client.server.mock.WatchEventsListener to allow list, because it is only used in the mock server.

Result:
Blockhound passes.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 0.00%. Comparing base (8150425) to head (43cf415).
⚠️ Report is 170 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main   #6287       +/-   ##
============================================
- Coverage     74.46%       0   -74.47%     
============================================
  Files          1963       0     -1963     
  Lines         82437       0    -82437     
  Branches      10764       0    -10764     
============================================
- Hits          61385       0    -61385     
+ Misses        15918       0    -15918     
+ Partials       5134       0     -5134     

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[github-actions]

🔍 Build Scan® (commit: 43cf415)

Job name	Status	Build Scan®
build-ubicloud-standard-16-jdk-8	✅	https://ge.armeria.dev/s/zf67d2j6ftkrw
build-ubicloud-standard-16-jdk-21-snapshot-blockhound	❌ (failure)	https://ge.armeria.dev/s/tpga4zkhd65sc
build-ubicloud-standard-16-jdk-17-min-java-17-coverage	✅	https://ge.armeria.dev/s/wlfs3fpd76jis
build-ubicloud-standard-16-jdk-17-min-java-11	❌ (failure)	https://ge.armeria.dev/s/2ct3fmiltivlk
build-ubicloud-standard-16-jdk-17-leak	✅	https://ge.armeria.dev/s/e3mtplt2ujrdi
build-ubicloud-standard-16-jdk-11	✅	https://ge.armeria.dev/s/zia3qdhptyrqg
build-macos-latest-jdk-21	✅	https://ge.armeria.dev/s/meztrwxfajcrm

[jrhee17]

It looks like the CI is still failing due to a blocking call. Can you check this?

[sh-cho]

@jrhee17 Ok let me check

[minwoox]

This should work, but I’d prefer not to add test-related code into the production codebase. What do you think about introducing a separate KubernetesTestBlockHoundIntegration class under the test directory?

[sh-cho]

Sounds good :)
I will try it

[minwoox]

Thanks! 👍 👍 👍

[jrhee17]

Sorry, still looks like the blockhound CI is failing

[minwoox]

Oops, let me also take a look.

[minwoox]

After we update the version from 6.x to 7.x, the test suite uses the embedded Vert.x server:
https://github.com/fabric8io/kubernetes-client/blob/ed36981b306116d0c896e53ec4f7a04c2a065a72/doc/MIGRATION-v7.md?plain=1#L26

Vert.x utilizes FastThreadLocalThread for its blocking worker threads which are classified as non-blocking by Netty's BlockHoundIntegration.
In order to solve this issue, I left my suggestion to the block hound:
reactor/BlockHound#516

Let's wait for their answer. 😉