Adds Spotless code formatter

[MitchellGale]

Description

Adds support for Spotless code formatter via ./gradlew spotlessApply and ./gradlew spotlessCheck. Apply applies the checks, check notifies which changes need to be applied.

Checks applied:

• Import order - sorts imports
• Remove unused imports
• Trim trailing whitespace
• End with newline
• Google Java format - https://github.com/google/google-java-format

Issues Resolved

opensearch-project#1101

Check List

• New functionality includes testing.
  • All tests pass, including unit test, integration test and doctest
• New functionality has been documented.
  • New functionality has javadoc added
  • New functionality has user manual doc added
• Commits are signed per the DCO using --signoff

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
For more information on following Developer Certificate of Origin and signing off your commits, please check here.

[codecov]

Codecov Report

Merging #288 (36e7f3b) into integ/spotless (f92e48c) will not change coverage.
The diff coverage is n/a.

❗ Current head 36e7f3b differs from pull request most recent head 18a75bd. Consider uploading reports for the commit 18a75bd to get more accurate results

@@                Coverage Diff                @@
##             integ/spotless     #288   +/-   ##
=================================================
  Coverage             97.39%   97.39%           
  Complexity             4608     4608           
=================================================
  Files                   401      401           
  Lines                 11408    11408           
  Branches                843      843           
=================================================
  Hits                  11111    11111           
  Misses                  290      290           
  Partials                  7        7           

Flag	Coverage Δ
sql-engine	97.39% <ø> (ø)

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[MaxKsyunz]

Have you seen this PR?
Can you use the googleJavaFormat line from there and import wildcards check?

And similarly to https://github.com/opensearch-project/OpenSearch/blob/main/gradle/formatting.gradle, can you try applying spotless to md and rst files as well?

RST files may be a headache (could break doctest) so if it does not work well, we can do it separately.

[Yury-Fridlyand]

Please, rebase to fix CI

[MitchellGale]

Have you seen this PR? Can you use the googleJavaFormat line from there and import wildcards check?

And similarly to https://github.com/opensearch-project/OpenSearch/blob/main/gradle/formatting.gradle, can you try applying spotless to md and rst files as well?

RST files may be a headache (could break doctest) so if it does not work well, we can do it separately.

Why should we use 1.15.0?

[Yury-Fridlyand]

FAILURE: Build failed with an exception.

* Where:
Build file '/home/runner/work/opensearch-project-sql/opensearch-project-sql/build.gradle' line: 83

* What went wrong:
A problem occurred evaluating root project 'opensearch-sql'.
> Could not find method spotless() for arguments [build_8w75flnn8q[43](https://github.com/Bit-Quill/opensearch-project-sql/actions/runs/5527388334/jobs/10083082365?pr=288#step:4:44)fb46rqwsp8d78$_run_closure2@57f6c75d] on root project 'opensearch-sql' of type org.gradle.api.Project.

[Yury-Fridlyand]

Can spotless verify/add license headers? If yes, please add this to configuration.
And the same with line endings (\n instead of \r\n).

[MaxKsyunz]

Why should we use 1.15.0?

It was the latest release at the time.

The key is to specify the version of rules being used. This avoids new versions of formatting rules forcing unrelated changes to a PR.

[MitchellGale]

Why should we use 1.15.0?

It was the latest release at the time.

The key is to specify the version of rules being used. This avoids new versions of formatting rules forcing unrelated changes to a PR.

Ah! That makes sense, thanks. Will specify version :)