[FLINK-40071][build] Bump jackson-bom to 2.21.4

[spuru9]

What is the purpose of the change

jackson-databind 2.21.3 is affected by several recently published CVEs (54512 through 54518). Bumping jackson-bom to 2.21.4 fixes all of them except 54515, which has no released fix in any jackson 2.x line yet (its announced fix versions 2.21.5/2.22.1 are unreleased, and 2.22.0 is also affected) — that one needs a follow-up once upstream ships.

Brief change log

• jackson-bom.version 2.21.3 → 2.21.4 in the root pom
• Updated the NOTICE files of the 11 modules bundling non-shaded jackson (jackson-annotations stays at 2.21, matching the bom)

Verifying this change

This change is a dependency version bump without code changes. All affected bundling modules build cleanly, and the bundled jackson-databind version inside the shaded jars (flink-sql-avro, flink-kubernetes, flink-python, flink-s3-fs-hadoop) was verified to be 2.21.4.

Does this pull request potentially affect one of the following parts:

• Dependencies (does it add or upgrade a dependency): (yes — jackson 2.21.3 → 2.21.4, patch release)
• The public API, i.e., is any changed class annotated with @Public(Evolving): (no)
• The serializers: (no)
• The runtime per-record code paths (performance sensitive): (no)
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Kubernetes/Yarn, ZooKeeper: (no)
• The S3 file system connector: (no)

Documentation

• Does this pull request introduce a new feature? (no)
• If yes, how is the feature documented? (not applicable)

---

Was generative AI tooling used to co-author this PR?

• Yes: Claude Code

Generated-by: Claude Code (claude-fable-5)

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CI report:

• 67faa8c Azure: SUCCESS

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[snuyanzin]

jackson-databind 2.21.3 is affected by several recently published CVEs (54512 through 54518). Bumping jackson-bom to 2.21.4 fixes all of them except 54515, which has no released fix in any jackson 2.x line yet (its announced fix versions 2.21.5/2.22.1 are unreleased, and 2.22.0 is also affected) — that one needs a follow-up once upstream ships.

existence of CVE in 3rd party doesn't necessary mean Flink is impacted

if we bump dependency now it doesn't mean a new Flink release, which means nothing is changed for end user.

So the question: why we should update now rather than wait for full fix from jackson and update?

[spuru9]

Ok will move to draft, and add this to the JIRA. Will open with the latest version close to the release.