exporters: support SLICE attributes

[pellared]

Fixes #8162

Note

I was testing #8215 using Codex CLI with GPT 5.4 Medium when working on this PR.

It worked very nice. Initially, I added only minimal changes in the code and some where caused by patterns that already existed and I do not agree with (e.g. usage of t.Parallel). I also added a comment in model.go and moved changed log entries from "Fixed" to "Added". Then I applied a few refinements and started addressing the Copilot review comments.

Follow-up to #8153 for attribute.SLICE.

Add end-to-end exporter handling for attribute.SLICE in the remaining paths that still treated it as invalid or relied on fallback formatting.

Changes:

• encode attribute.SLICE as OTLP AnyValue_ArrayValue for trace, log, and metric transforms
• serialize Zipkin SLICE attributes using the non-OTLP AnyValue string representation
• add trace-side coverage for recursive convAttrValue slice conversion

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.6%. Comparing base (3384d39) to head (5d0599b).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #8216     +/-   ##
=======================================
+ Coverage   82.5%   82.6%   +0.1%     
=======================================
  Files        310     310             
  Lines      24595   24647     +52     
=======================================
+ Hits       20305   20375     +70     
+ Misses      3913    3893     -20     
- Partials     377     379      +2     

Files with missing lines	Coverage Δ
...otlp/otlplog/otlploggrpc/internal/transform/log.go	96.3% <100.0%> (+0.1%)	⬆️
...otlp/otlplog/otlploghttp/internal/transform/log.go	96.3% <100.0%> (+0.1%)	⬆️
...ric/otlpmetricgrpc/internal/transform/attribute.go	97.0% <100.0%> (+0.3%)	⬆️
...ric/otlpmetrichttp/internal/transform/attribute.go	97.0% <100.0%> (+0.3%)	⬆️
...tlp/otlptrace/internal/tracetransform/attribute.go	97.1% <100.0%> (+0.3%)	⬆️
exporters/zipkin/model.go	99.4% <100.0%> (+<0.1%)	⬆️

... and 2 files with indirect coverage changes

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[Copilot]

Pull request overview

Adds end-to-end handling of attribute.SLICE across remaining exporter/transform paths so slice attributes are preserved instead of being treated as invalid or falling back to formatting.

Changes:

• Encode attribute.SLICE as OTLP AnyValue_ArrayValue for trace, log, and metric attribute transforms (including shared templates + generated outputs).
• Add regression tests for slice conversion (trace/auto, OTLP trace transform, OTLP log/metric transforms, Zipkin string serialization).
• Update CHANGELOG.md with new SLICE exporter support entries.

Reviewed changes

Copilot reviewed 18 out of 18 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
trace/auto_test.go	Adds recursive slice conversion coverage for convAttrValue.
internal/shared/otlp/otlpmetric/transform/attribute.go.tmpl	Adds attribute.SLICE → OTLP ArrayValue conversion in metric transform template.
internal/shared/otlp/otlpmetric/transform/attribute_test.go.tmpl	Adds slice transform tests/fixtures to metric template tests.
internal/shared/otlp/otlplog/transform/log.go.tmpl	Adds attribute.SLICE → OTLP ArrayValue conversion in log transform template.
internal/shared/otlp/otlplog/transform/attr_test.go.tmpl	Adds slice transform tests/fixtures to log template tests.
exporters/otlp/otlptrace/internal/tracetransform/attribute.go	Adds attribute.SLICE → OTLP ArrayValue conversion for trace exporter transform.
exporters/otlp/otlptrace/internal/tracetransform/attribute_test.go	Adds trace transform regression coverage for slice → array conversion.
exporters/otlp/otlplog/otlploggrpc/internal/transform/log.go	Enables SLICE conversion for OTLP log gRPC path.
exporters/otlp/otlplog/otlploggrpc/internal/transform/attr_test.go	Adds SLICE regression tests for OTLP log gRPC path.
exporters/otlp/otlplog/otlploghttp/internal/transform/log.go	Enables SLICE conversion for OTLP log HTTP path.
exporters/otlp/otlplog/otlploghttp/internal/transform/attr_test.go	Adds SLICE regression tests for OTLP log HTTP path.
exporters/otlp/otlpmetric/otlpmetricgrpc/internal/transform/attribute.go	Enables SLICE conversion for OTLP metric gRPC path.
exporters/otlp/otlpmetric/otlpmetricgrpc/internal/transform/attribute_test.go	Adds SLICE regression tests for OTLP metric gRPC path.
exporters/otlp/otlpmetric/otlpmetrichttp/internal/transform/attribute.go	Enables SLICE conversion for OTLP metric HTTP path.
exporters/otlp/otlpmetric/otlpmetrichttp/internal/transform/attribute_test.go	Adds SLICE regression tests for OTLP metric HTTP path.
exporters/zipkin/model.go	Adds best-effort SLICE serialization using Value.String() AnyValue formatting.
exporters/zipkin/model_test.go	Adds Zipkin SLICE serialization regression test.
CHANGELOG.md	Documents SLICE exporter support in Unreleased notes.

[Copilot]

Pull request overview

Copilot reviewed 21 out of 21 changed files in this pull request and generated 3 comments.

[Copilot]

Pull request overview

Copilot reviewed 21 out of 21 changed files in this pull request and generated no new comments.