test: Roll SLF4J log4j bindings to v2

[scottgerring]

Issue #, if available: #1180

Description of changes:

We generally couple directly against Log4j, but in a couple of places we write to the slf4j API, which is then adapted back to log4j by log4j's log4j-slf4j-impl package:

https://github.com/awslabs/aws-lambda-powertools-java/blob/76ca20f2df7631b6cf4eaed852a55ab95f27be1d/powertools-serialization/pom.xml#L52-L55

Because this adapter is being pulled in by our code and is using slf4j-v1, customers using slf4j-v2 themselves can have issues using the powertools (see #1180). This PR switches the adapter to slf4j-v2.

Long term we intend to switch to slf4j (#995, #965), rather than coupling directly against log4j. As this will be a breaking change, it has been earmarked for powertools for java v2.

Checklist

• Meet tenets criteria
• Update tests
• Update docs
• PR title follows conventional commit semantics

Breaking change checklist

RFC issue #:

• Migration process documented
• Implement warnings (if it can live side by side)

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[scottgerring]

@jeromevdl what do you think? This seems pretty harmless to me, and the slf4j upgrade-to-v2 FAQ lists it as a non-breaking change.

I have also tried to document explicitly on this PR the state of logging in the repo and our long term plans here.

[codecov-commenter]

Codecov Report

Patch and project coverage have no change.

Comparison is base (7f804fe) 70.87% compared to head (5d0570c) 70.87%.

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Additional details and impacted files

@@            Coverage Diff            @@
##               main    #1190   +/-   ##
=========================================
  Coverage     70.87%   70.87%           
  Complexity      541      541           
=========================================
  Files            72       72           
  Lines          2328     2328           
  Branches        254      254           
=========================================
  Hits           1650     1650           
  Misses          558      558           
  Partials        120      120           

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[jeromevdl]

Looks ok.

That's all the slf4j reference we have ? I still don't understand why we introduced slf4j here...

@msailes any reason for this; Was it to fix a warning in the log: #123 ?

[scottgerring]

Looks ok.

That's all the slf4j reference we have ? I still don't understand why we introduced slf4j here...

@msailes any reason for this; Was it to fix a warning in the log: #123 ?

You can see that some of our code couples against it instead of log4j. I don't know if it was initially an autocomplete accident or good intentions ("we should be using slf4j not log4j").

[jeromevdl]

@scottgerring anything else to do on this one? it is marked as draft...