Jaeger Exporter: Fix minor mapping discrepancies

[matej-g]

The specification for Jaeger exporter specifies a number of requirements on how the span data should be mapped between OpenTelemetry and Jaeger.

This PR intends to correct some minor discrepancies which have been found previously, in particular:

• Instrumentation library name / version key should be otel.library.* instead of otel.instrumentation_library.* (relevant section)
• SpanKind.INTERNAL should not be added to tags (relevant section).
• Do not include status code tag if the span status is UNSET (relevant section).
• Do not ignore array attributes; serialize them to string as JSON list (relevant section).
• Links should have reference type FOLLOWS_FROM (relevant section).

Includes also test changes.

Related issue

One aspect that remain unclear to me, which is not addressed in this PR, I have described in #1625

Resolves (partially) #1376.

[codecov]

Codecov Report

Merging #1626 (163355b) into main (238e7c6) will increase coverage by 0.0%.
The diff coverage is 100.0%.

@@          Coverage Diff          @@
##            main   #1626   +/-   ##
=====================================
  Coverage   77.3%   77.3%           
=====================================
  Files        128     128           
  Lines       6682    6693   +11     
=====================================
+ Hits        5167    5180   +13     
+ Misses      1268    1266    -2     
  Partials     247     247           

Impacted Files	Coverage Δ
exporters/trace/jaeger/jaeger.go	93.4% <100.0%> (+0.4%)	⬆️
exporters/otlp/otlpgrpc/connection.go	88.7% <0.0%> (+1.8%)	⬆️

[ijsong]

@matej-g
It seems that the jaeger exporter has a different tag for InstrumentationLibrary. I am not sure what is correct.

	TagInstrumentationName    = "otlp.instrumentation.library.name"
	TagInstrumentationVersion = "otlp.instrumentation.library.version"

https://github.com/open-telemetry/opentelemetry-collector/blob/27b27b75a53e5dd596a8862d931a7aad4992c3d6/translator/trace/protospan_translation.go#L44-L45

[matej-g]

It seems that the jaeger exporter has a different tag for InstrumentationLibrary. I am not sure what is correct.

Not sure what the requirements are for the collector, but as it stands in the specification, I believe otel.library.* should be correct here. Same key is being used by implementations in other languages e.g. Java or Rust.