[SPARK-30159][SQL][FOLLOWUP] Fix lint-java via removing unnecessary imports

[HeartSaVioR]

What changes were proposed in this pull request?

This patch fixes the Java code style violations in SPARK-30159 (#26788) which are caught by lint-java (Github Action caught it and I can reproduce it locally). Looks like Jenkins build may have different policy on checking Java style check or less accurate.

Why are the changes needed?

Java linter starts complaining.

Does this PR introduce any user-facing change?

No.

How was this patch tested?

lint-java passed locally

This closes#26819

[dongjoon-hyun]

Thank you, @HeartSaVioR !

[dongjoon-hyun]

+1, LGTM. This passed GitHub Action linter.
Merged to master.

[gengliangwang]

@HeartSaVioR Thanks for the follow-up

[SparkQA]

Test build #115044 has finished for PR 26818 at commit 84d6466.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[HeartSaVioR]

Thanks all for reviewing and merging!

[HyukjinKwon]

Thanks for fixing it. Hm, I wonder why there's a diff ...

[HeartSaVioR]

Hm, I wonder why there's a diff ...

#26820 seems to be an answer; we don't fail the build even though there're style guide violations. In script of Github Action, we run lint-java which fails the build.

[dongjoon-hyun]

Yes.

• GitHub Action showed a failure at the last commit, but it was ignored.
• Inside Jenkins, the following job died, but the others didn't.
• https://amplab.cs.berkeley.edu/jenkins/view/Spark%20QA%20Test%20(Dashboard)/job/spark-master-test-sbt-hadoop-3.2/

[HyukjinKwon]

I mean, Jenkins uses sbt-checkstyle via SBT to reuse previously compiled results. Github Action usese Maven linter. Seems there's a difference between them.

I don't believe the linter doesn't fail in PR builder if this isn't a regression - I tested it when I added it.