[FLINK-21160][connector/kafka] Fix bug of referencing uninitialized deserializer when using KafkaRecordDeserializer#valueOnly

[PatrickRen]

What is the purpose of the change

This pull request fixes bug of referencing uninitialized deserializer in ValueDeserializerWrapper when using KafkaRecordDeserializer#valueOnly, which would lead to NPE at job compiling stage.

Brief change log

• Keep the deserializeClass directly in the instance of ValueDeserializerWrapper as a member instead of storing the name of the class
• Add an IT case for testing value only deserializer.

Verifying this change

• Added integration tests for using KafkaRecordDeserializer#valueOnly to build a KafkaSource

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

• Dependencies (does it add or upgrade a dependency): (no)
• 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/Mesos, 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)

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Automated Checks

Last check on commit c327e27 (Thu Jan 28 03:55:21 UTC 2021)

Warnings:

• No documentation files were touched! Remember to keep the Flink docs up to date!
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CI report:

• e82fe2a Azure: SUCCESS Azure: FAILURE Azure: SUCCESS

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[lindong28]

Thanks for the PR. The PR looks good to me. I verified that the test fails before the change and passes after the change.

Ping @becketqin for review.

[lindong28]

@flinkbot run azure

[PatrickRen]

I investigated two Azure builds and both two CI failure are caused by E2E tests. The first E2E run was timed out, and the second one failed because of a K8S session test, looks like K8S deployment failure. I'm not quite familiar with K8S but it seems irrelevant with this PR.

I'll trigger Azure build again for another try.

[PatrickRen]

@flinkbot run azure

[HuangXingBo]

Hi @PatrickRen The failed python test has been resolved in FLINK-21216. I think you need to rebase master and push again.

[lindong28]

@PatrickRen It is better to rebase PR onto master HEAD (particularly if the PR is more than several days older) in such cases. It is because we need to do best effort to make sure the PR passes all tests in the master HEAD. And it is possible that the bug has already been fixed in the HEAD.

[PatrickRen]

Thank you @HuangXingBo and @lindong28 ! I just rebased the branch to master and pushed again. Hope we can pass all tests on Azure this time~

[PatrickRen]

@flinkbot run azure

[PatrickRen]

Finally we have a successfully run Azure build. @becketqin @lindong28 Could you please have a review on this PR? Thanks~

[lindong28]

Thanks for the update! LGTM.

[becketqin]

@flinkbot run azure

[becketqin]

Thanks for the patch. LGTM.

Merged to master:
844601b