Enable automatic integration with OpenTelemetry Java agent while maintaining full backwards compatibility with standalone tracing configuration.

Fixes#27638

Changes

• Add ConditionalTracingModule that auto-detects GlobalOpenTelemetry
• Add GlobalOpenTelemetryModule to bind global instance when detected
• Update Server.java to use ConditionalTracingModule
• Add tests for auto-detection and override behavior
• Update OpenTelemetry documentation with Java agent integration guide

Behavior

When Java agent is present:

• Auto-detects GlobalOpenTelemetry and uses it (logged as "Using GlobalOpenTelemetry")
• All spans share resource attributes from agent
• Configuration done once via agent (OTEL_* env vars)
• Single exporter, single SDK instance

When Java agent is NOT present:

• Falls back to TracingModule (logged as "Using dedicated TracingModule")
• Existing tracing.* configuration works unchanged
• 100% backwards compatible

Override

System property or environment variable to force specific behavior:

Force use of global

-Dtracing.use-global=true
export TRACING_USE_GLOBAL=true

Force use of dedicated TracingModule

-Dtracing.use-global=false

Testing

Unit tests verify:

• Auto-detection when GlobalOpenTelemetry is initialized
• Fallback when not initialized
• System property override
• Backwards compatibility

Documentation

• docs/src/main/sphinx/admin/opentelemetry.md: Added Java agent integration section
• docs/src/main/sphinx/develop/opentelemetry-java-agent.md: Developer guide

Description

Additional context and related issues

Release notes

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##OpenTelemetry* Fix integration with opentelemetry javaagent (duplicate instances). ({issue}`27638`)