fix: Use makeCopy to change relation in FileSourceScanExec

[viirya]

Which issue does this PR close?

Relates #190.

Rationale for this change

What changes are included in this PR?

How are these changes tested?

[viirya]

mapProductIterator in class TreeNode cannot be accessed in org.apache.spark.sql.execution.FileSourceScanExec

Ah, mapProductIterator is protected method. Let me update this later.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 84.61538% with 2 lines in your changes are missing coverage. Please review.

❗ No coverage uploaded for pull request base (main@9aa42cd). Click here to learn what that means.

Files	Patch %	Lines
...ala/org/apache/spark/sql/comet/CometScanExec.scala	84.61%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #207   +/-   ##
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  Coverage        ?   33.33%           
  Complexity      ?      769           
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  Files           ?      107           
  Lines           ?    35406           
  Branches        ?     7673           
=======================================
  Hits            ?    11804           
  Misses          ?    21147           
  Partials        ?     2455           

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[comphead]

perhaps we can also consider CometScanExec extends TreeNode to remove mapProductIterator method copy?

[viirya]

We want to run mapProductIterator on FileSourceScanExec. I'm not sure how object CometScanExec extends TreeNode can help us?

[comphead]

You are right, its needed to run mapProductIterator on FileSourceScanExec, I wrongly assumed this method needed for CometScanExec .

[viirya]

This patch cannot completely resolve the ticket #190 but only fixes the first error. After the first error is fixed, there comes out another API incompatibility issue around DataSourceScanExec.

I think it is still good to have this patch to fix the first error.

[comphead]

lgtm thanks @viirya

[viirya]

Merged. Thanks.