[FLINK-20292][doc] Improve the document about table formats overlap in user fat jar

[leonardBang]

What is the purpose of the change

• Currently, Flink can not load the right format factory if users' fat jar using more than one format, the reason is the SPI configuration file META/services will overlap each other. User can use maven shade plugin to skip this issue, this pull request improves the document about table formats overlap in user fat jar,

Brief change log

• Add note about using maven shade plugin to skip formats configuration files overlap in table formats overview page.

Verifying this change

This change is a document improvement without any test coverage.

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, 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 / docs / JavaDocs / not documented)

[leonardBang]

cc : @gaoyunhaii Appreciate if you can take a look this PR.

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[gaoyunhaii]

Very thanks @leonardBang for opening the PR ! I thought that we may also

1. Explicitly adding codes to show how to configure maven shaded plugin under the description.
2. Links to this section from the specific format pages (like avro) under the Dependencies section so that users jump to specific pages could also see the warnings.

How do you think about that ?

[leonardBang]

Very thanks @leonardBang for opening the PR ! I thought that we may also

1. Explicitly adding codes to show how to configure maven shaded plugin under the description.
2. Links to this section from the specific format pages (like avro) under the Dependencies section so that users jump to specific pages could also see the warnings.

How do you think about that ?

make sense to me, will update the PR

[leonardBang]

@gaoyunhaii Appreciate if you can take a look ^_^.

[leonardBang]

@gaoyunhaii Could you have a more look?

[gaoyunhaii]

Very thanks @leonardBang for the updates ! The PR looks good to me now and +1 for merge!

[JingsongLi]

+1

[JingsongLi]

Links to this section from the specific format pages (like avro) under the Dependencies section so that users jump to specific pages could also see the warnings.

I think this is a little redundant, we don't need add same words in every formats, what do you think? @gaoyunhaii @leonardBang

[gaoyunhaii]

From my side of view I still tend to keep the links since that if users want to add the dependency of one format, he would tend to jump to the corresponding page to see how to add the dependency, without read the index page first.

[leonardBang]

I think we need add a section for connector/index page.
And do we to add NOTE for every connector and format ? I tend to do not, building an uber-jar is not necessary for SQL user, many user case is downloading the connector jar and format jar directly, if user's project contains multiple connectors/formats, I think user will read connectors/formats matrix in index page.

[gaoyunhaii]

Ok, got it, if building an uber-jar is not necessary for SQL user, then I think it should be ok to not add the note. Very thanks for the information!

[leonardBang]

@gaoyunhaii @JingsongLi Updated as discussed

[JingsongLi]

Looks good to me. Thanks @leonardBang and @gaoyunhaii , merging...