[FLINK-12190] Fix IllegalArgumentException thrown by FlinkKinesisConsumerMigrationTest#writeSnapshot

[yanghua]

What is the purpose of the change

This pull request fixes IllegalArgumentException thrown by FlinkKinesisConsumerMigrationTest#writeSnapshot

Brief change log

• Fix IllegalArgumentException throwed by FlinkKinesisConsumerMigrationTest#writeSnapshot

Verifying this change

This change is already verified by commits 86e33fe36ed29b6e01dd7fe4151a8650ad25612c in PR #8168 *.

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

• Dependencies (does it add or upgrade a dependency): (yes / no)
• The public API, i.e., is any changed class annotated with @Public(Evolving): (yes / no)
• The serializers: (yes / no / don't know)
• The runtime per-record code paths (performance sensitive): (yes / no / don't know)
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Yarn/Mesos, ZooKeeper: (yes / no / don't know)
• The S3 file system connector: (yes / no / don't know)

Documentation

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

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[yanghua]

@tzulitai The Travis is failed because of Kafka connector IT test case, I have reported an issue: FLINK-12196.

[zentol]

Please expand the description. It should explain what the underlying problem is and how your solutio addresses it.

[yanghua]

@zentol Sorry, I have added more details. It is because the exists code did not initialize TestFetcher correctly. Actually, there is a discussion in FLINK-10785. I have discussed with @tzulitai about the solution before.

[yanghua]

@tzulitai Can you review this PR? thanks.

[yanghua]

@tzulitai I think this PR can make sense for someone who wants to do the migration test after releasing Flink 1.9. If you have time, can you review this PR? thanks.

[tzulitai]

Sorry for the late review on this one. LGTM, +1.
Merging ..

[yanghua]

Hi @tzulitai I think this PR can also be merged. WDYT?

[tzulitai]

Merging ...