[FLINK-11820][serialization] SimpleStringSchema handle message record which value is null

[lamberken]

What is the purpose of the change

when kafka msg queue contains some records which value is null, SimpleStringSchema can't process these records.

for example, msg queue like bellow.

msg

null

msg

msg

msg

for normal, use SimpleStringSchema to process msg queue data

env.addSource(new FlinkKafkaConsumer010("topic", new SimpleStringSchema(), properties));

but, will get NullPointerException

java.lang.NullPointerException
	at java.lang.String.<init>(String.java:515)
	at org.apache.flink.api.common.serialization.SimpleStringSchema.deserialize(SimpleStringSchema.java:75)
	at org.apache.flink.api.common.serialization.SimpleStringSchema.deserialize(SimpleStringSchema.java:36)

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[klion26]

Nice catch, and thank you for your contribution @lamber-ken. we should avoid git merge in the git history and use git rebase instead.

I not every sure whether we have to add a ut for this.

[lamberken]

@klion26, I see, thanks.

[lamberken]

@klion26, hi, I have updated the pr as you suggest, thanks

[lamberken]

@klion26，cc

[klion26]

thanks for you contribution, LGTM now

[carp84]

@aljoscha @tzulitai Mind take a look here? Thanks.

[PierreZ]

Hi!

Quick message to say that we hit the same problem this week, and applied a similar patch that mitigated the issue.

[lamberken]

hi, @GJL @tillrohrmann, this pr fix NPE in some scenarioscan, can you take a look here? Thanks.

[lamberken]

Hi @GJL,

Thanks for your review and your comment is great for me. But my branch has been deleted unexpectly, so I can't commit anything, need I open a new PR?

[GJL]

@lamber-ken I think yes. You can try to recover the commits via: https://help.github.com/en/articles/checking-out-pull-requests-locally

[lamberken]

@lamber-ken I think yes. You can try to recover the commits via: https://help.github.com/en/articles/checking-out-pull-requests-locally

@GJL, I open a new PR, and update it as your comment, see #8583