[FLINK-38062][table] ENCODE function behaves wrong

[snuyanzin]

What is the purpose of the change

The PR fixes the behavior of ENCODE as mentioned in jira issue

Brief change log

Verifying this change

The test added under MiscFunctionsITCase.java

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): (yes / no / don't know)
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Kubernetes/Yarn, ZooKeeper: ( no )
• The S3 file system connector: (yes)

Documentation

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

[flinkbot]

CI report:

• 2a252ff Azure: SUCCESS

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[twalthr]

Added some last nit comments. Feel free to merge afterwards.

[liuyongvs]

LGTM +1

[snuyanzin]

Should we remove nullableIfArgs in BuiltInFunctionDefinitions#ENCODE? Same for DECODE.

why ?

SELECT encode(cast(null as string), 'utf-8'), encode(cast(null as string), cast(null as string)), encode('asd', cast(null as string));

returns

null, null, null

or did I miss anything?

[dylanhz]

Should we remove nullableIfArgs in BuiltInFunctionDefinitions#ENCODE? Same for DECODE.

why ?

SELECT encode(cast(null as string), 'utf-8'), encode(cast(null as string), cast(null as string)), encode('asd', cast(null as string));

returns

null, null, null

or did I miss anything?

I mean the nullability of return types are different in BuiltInFunctionDefinitions and FlinkSqlOperatorTable .

[snuyanzin]

can you log an issue for that with description and a test case then?
We can continue discussion there and fix if required

[dylanhz]

can you log an issue for that with description and a test case then?
We can continue discussion there and fix if required

OK. And this pr LGTM.