CI: Add linter check for scala

[ljubon]

The goal of this PR is to enable CI to have linter enabled and basic rules defined in .github/workflows/linter.yml

[github-actions]

Test Results

0 files   -      573  0 suites   - 573   0s ⏱️ - 2h 47m 57s
0 tests  -      525  0 ✔️  -      505  0 💤 ±0  0 ❌ ±0 
0 runs   - 16 268  0 ✔️  - 16 246  0 💤  - 2  0 ❌ ±0 

Results for commit d26497c. ± Comparison against base commit 47b901b.

[pavlovic-ivan]

Hi @EnricoMi! Hope you are doing good. Can you please take another look at this PR, as changes have been made as requested

[EnricoMi]

How can we run scalafmt from command line / mvn so that developer can auto-format the code?

[EnricoMi]

We can make scalafmt part of mvn compile so that this is checked during development:

• add to pom.xml: https://github.com/G-Research/spark-extension/pull/201/files#diff-9c5fb3d1b7e3b0f54bc5c4182965c4fe1f9023d449017cece3005d3f90e8e4d8
• run in compile phase: https://github.com/G-Research/spark-extension/pull/212/files#diff-9c5fb3d1b7e3b0f54bc5c4182965c4fe1f9023d449017cece3005d3f90e8e4d8R247-R256

No need to add this specifically to CI then.

[ljubon]

How can we run scalafmt from command line / mvn so that developer can auto-format the code?

locally from CLI you can run scalafmt --test

[ljubon]

We can make scalafmt part of mvn compile so that this is checked during development:

• add to pom.xml: https://github.com/G-Research/spark-extension/pull/201/files#diff-9c5fb3d1b7e3b0f54bc5c4182965c4fe1f9023d449017cece3005d3f90e8e4d8
• run in compile phase: https://github.com/G-Research/spark-extension/pull/212/files#diff-9c5fb3d1b7e3b0f54bc5c4182965c4fe1f9023d449017cece3005d3f90e8e4d8R247-R256

No need to add this specifically to CI then.

How would you like to proceed with this PR? Should I adopt this PR and use mvn compile or is this current implementation already part of it?

[EnricoMi]

I'd prefer #201 and #212 over this.

[ljubon]

I'd prefer #201 and #212 over this.

That's ok from my side, @pavlovic-ivan your thoughts?
I would propose to keep this PR as monitoring until #201 #212 are merged as we would like to bring these changes as part of the maturity matrix for all OSS projects
Also if you need any help/support for open PRs I'm available to support

[pavlovic-ivan]

I am good with suggested as well

[EnricoMi]

All merged.

[ljubon]

Thank you @EnricoMi! will close this PR as issue is resolved with PR mentioned