Fix dockerPackageMappings to be absolute paths

[joan38]

Fixes #1304

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[muuki88]

Thanks for the bug report and the pull request to fix this 🤗

There are a couple of things that make me hesitate to merge this

• the issues seems to be in the MappingsHelper if the paths that are returned are not correct
• using Paths seems like a good workaround, but I'm not sure if this is a maintainable solution as this relies heavily on the underlying OS (e.g. file separators, how path representation works )
• a regression test that demonstrates the fix would always be nice

[joan38]

I don't think MappingsHelper has any issue since it returns relative paths by design.

Your concerne about the underlying OS would be an issue if we are using a different OS in the docker image we are building (not the host machine that is running SBT).

I will add a test for it.

[muuki88]

Hi @joan38 thanks again for tackeling this 😃
Do you know if you have the time to add some tests for this?

[joan38]

Hi @muuki88, I'm not sure I'll have much time to do this also since we moved away from SBT to Mill.

[muuki88]

Thanks for the update @joan38 😊