[FLINK-25895][table-planner] Splitted ExecNodeGraphJsonPlanGenerator

[slinkydeveloper]

What is the purpose of the change

This PR reorganizes a bit the code that was previously in ExecNodeGraphJsonPlanGenerator. It introduces ExecNodeGraph ser/de to handle the intermediate JsonPlanGraph representation directly.

Brief change log

• Reorg the code in ExecNodeGraphJsonPlanGenerator in:
  • Moved to the upper level the intermediate graph model (and made it package private)
  • Removed unnecessary intermediate methods
  • Isolated the validator in a separate class

Verifying this change

This change is a trivial rework / code cleanup 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

Documentation

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

[flinkbot]

CI report:

• d34a3cb Azure: FAILURE

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Automated Checks

Last check on commit d25cacc (Mon Jan 31 15:06:39 UTC 2022)

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[slinkydeveloper]

@matriv given your two comments, does it makes sense to just go ahead and remove this validator?

[matriv]

@matriv given your two comments, does it makes sense to just go ahead and remove this validator?

Yes, the @JsonCreator is tested statically when we build the lookupMap in the ExecNodeMetadataUtil, and the other is always checked for not null in the ctor, so go ahead and completely remove it.

[matriv]

LGTM, left some minor comments.

[matriv]

LGTM!

[slinkydeveloper]

I reverted the removal of ExecNodeGraphValidator, as it seems like because of legacy tables, TemporalTableSourceSpec can be initiated with empty DynamicTableSourceSpec.

[twalthr]

LGTM