[#6486] feat(iceberg): supports change Iceberg request in pre event listener

[FANNG1]

What changes were proposed in this pull request?

Use an wrapper class to allow user create an new request, and the dispatcher operator use the new created request. The event listener could leverage ObjectWrapper to create new Iceberg request.

  public void onPreEvent(PreEvent preEvent) {
    if (preEvent instanceof IcebergCreateTablePreEvent) {
      ObjectWrapper<CreateTableRequest> objectWrapper = ((IcebergCreateTablePreEvent) preEvent).createTableRequestWrapper();
      CreateTableRequest originalRequest = objectWrapper.get();
      // create newRequest according to your business logic
      objectWrapper.set(newRequest);
    }
  }

Why are the changes needed?

Fix: #6486

Does this PR introduce any user-facing change?

no

How was this patch tested?

change the iceberg request and it take affects when creating table in local enviroment

[FANNG1]

@jerryshao @puchengy PTAL.

[puchengy]

@FANNG1 LGTM, can we also support Update table as well to begin with? Thanks

[tengqm]

I have a concern with this piece solution. Either we need to augment the create table request to meet the requirement, or we need a global solution for events. By global solution, I mean we may need a wrapper pattern for all events. Of course we can get his one case handled today, but in the long run, we have to make sure the same thing won't happen again.

[FANNG1]

@puchengy @tengqm thanks for your advise, use a more general solution by objectWrapper to wrap the Iceberg REST request in pre event, please help to review again.

[tengqm]

Regarding this PR, I think it is clean and okay to go ahead.
Wondering if we need an umbrella issue for handling other events so that we won't get the ball dropped.

[puchengy]

what is this function used for? I can't find the caller. Same questions for similar functions in the preEvent classes.

[FANNG1]

event listener invokes this function to get ObjectWrapper and set an new CreateTableRequest

[puchengy]

@FANNG1 Is this an upcoming change or is this included in the PR? I searched around but do not see where this method is called.

[FANNG1]

There is no upcoming changes, it's the responsibility of end users to provide custom event listeners, like

  public void onPreEvent(PreEvent preEvent) {
    if (preEvent instanceof IcebergCreateTablePreEvent) {
      ObjectWrapper<CreateTableRequest> objectWrapper = ((IcebergCreateTablePreEvent) preEvent).createTableRequestWrapper();
      CreateTableRequest originalRequest = objectWrapper.get();
      // create newRequest according to your business logic
      objectWrapper.set(newRequest);
    }
  }