Add guidelines for breaking changes

[jpkrohling]

As a result of the discussion involving #4672, we agreed during the SIG Collector meeting that we'd start recommending and enforcing breaking changes to be performed in two steps.

Signed-off-by: Juraci Paixão Kröhling juraci@kroehling.de

[jpkrohling]

@dashpole, do you have a good resource about how to do feature flags in the collector? If so, I'll add a link.

[codecov]

Codecov Report

Merging #4712 (d455eb2) into main (04baaae) will decrease coverage by 0.05%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main    #4712      +/-   ##
==========================================
- Coverage   90.78%   90.73%   -0.06%     
==========================================
  Files         180      179       -1     
  Lines       10637    10696      +59     
==========================================
+ Hits         9657     9705      +48     
- Misses        761      770       +9     
- Partials      219      221       +2     

Impacted Files	Coverage Δ
internal/cgroups/cgroups.go	87.67% <0.00%> (-4.00%)	⬇️
receiver/otlpreceiver/otlp.go	80.55% <0.00%> (-0.78%)	⬇️
config/confighttp/confighttp.go	100.00% <0.00%> (ø)
config/configmapprovider/properties.go	100.00% <0.00%> (ø)
config/service.go
service/internal/configprovider/expand.go
config/configmapprovider/expand.go	100.00% <0.00%> (ø)
exporter/otlphttpexporter/otlp.go	82.20% <0.00%> (+0.15%)	⬆️
service/config_provider.go	91.96% <0.00%> (+0.37%)	⬆️
service/flags.go	86.36% <0.00%> (+0.64%)	⬆️
... and 2 more

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[bogdandrutu]

do you have a good resource about how to do feature flags in the collector? If so, I'll add a link.

https://github.com/open-telemetry/opentelemetry-collector/tree/main/service/featuregate

But as I explained, these are not helping with API changes.

[bogdandrutu]

@codeboten lots of changes since your review, I asked you to do another round please.

[tigrannajaryan]

LGTM. This reflects our intent. Any further clarifications can be added via additional PRs.

[tigrannajaryan]

@jpkrohling I can merge this once the comments are resolved.

[jpkrohling]

PR updated. I think there's only one open comment about features being replaced by existing ones. Not sure there's anything to do in the other open comment.

[jpkrohling]

Not sure there's anything to do in the other open comment.

That one was resolved, only one comment is still open but I think it has been addressed already.