[OTLP] Update HttpClientFactory documentation

[martincostello]

Fixes #7575

Changes

• Update out-of-date notes about the logging integration (see [Exporter.OTLP] Enable IHttpClientFactory for OtlpLogExporter #7109 and [OTLP] Enable HttpClientFactory for logs #7298).
• Document that .NET 5+ must override DelegatingHandler.Send().

Merge requirement checklist

• CONTRIBUTING guidelines followed (license requirements, nullable enabled, static analysis, etc.)
• Unit tests added/updated
• Appropriate CHANGELOG.md files updated for non-trivial changes
• Changes in public API reviewed (if applicable)

[opentelemetry-pr-dashboard]

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Waiting on reviewers · refreshed 2026-07-31 19:36 UTC

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[martincostello]

This uses <c> instead of <see> as the symbol only exists for some TFMs, and dotnet format doesn't like #if constructs in the middle of /// sections.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.38%. Comparing base (fc163d4) to head (8f94e75).
⚠️ Report is 1 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7577      +/-   ##
==========================================
- Coverage   90.44%   90.38%   -0.07%     
==========================================
  Files         290      290              
  Lines       15989    15989              
==========================================
- Hits        14462    14452      -10     
- Misses       1527     1537      +10     

Flag	Coverage Δ
unittests-Project-Experimental	90.49% <ø> (ø)
unittests-Project-Stable	90.27% <ø> (-0.23%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.
see 4 files with indirect coverage changes

[Copilot]

Pull request overview

Updates OTLP exporter documentation to reflect current IHttpClientFactory support (including logs) and to clarify DelegatingHandler requirements for .NET 5+ when customizing authentication/headers via handlers.

Changes:

• Document customizing named HttpClient instances for "OtlpTraceExporter", "OtlpMetricExporter", and "OtlpLogExporter" via AddHttpClient.
• Add an IMPORTANT note that custom DelegatingHandler implementations targeting .NET 5+ must override both SendAsync and Send to ensure handler logic runs for all OTLP exporter requests.
• Update IOtlpExporterOptions XML docs to reflect logging registration’s IHttpClientFactory behavior and the DelegatingHandler override requirement.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/OpenTelemetry.Exporter.OpenTelemetryProtocol/README.md	Updates IHttpClientFactory guidance to include logs and adds guidance about overriding DelegatingHandler.Send/SendAsync on .NET 5+.
src/OpenTelemetry.Exporter.OpenTelemetryProtocol/IOtlpExporterOptions.cs	Updates XML documentation to reflect current logging integration behavior and handler override requirements.

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