[BUG] Documented telemetry.otel.tracer.span.exporter.class setting not recognized in OpenSearch 2.17.1 and 2.19.1

[kochango]

Describe the bug

The distributed tracing documentation at https://docs.opensearch.org/latest/observing-your-data/trace/distributed-tracing describes using telemetry.otel.tracer.span.exporter.class to configure the OTLP exporter, but this setting is not recognized by OpenSearch and causes startup failure.

OpenSearch fails to start with:

org.opensearch.bootstrap.StartupException: java.lang.IllegalArgumentException: unknown setting [telemetry.otel.tracer.span.exporter.class] please check that any required plugins are installed, or check the breaking changes documentation for removed settings.

Related component

Other

To Reproduce

1. Start OpenSearch 2.19.1 (or 2.17.1) with the experimental telemetry feature enabled:
   OPENSEARCH_JAVA_OPTS="-Dopensearch.experimental.feature.telemetry.enabled=true"

2. Add the following to opensearch.yml:
   telemetry.feature.tracer.enabled: true
   telemetry.tracer.enabled: true
   telemetry.otel.tracer.span.exporter.class: io.opentelemetry.exporter.otlp.trace.OtlpGrpcSpanExporter

3. Start OpenSearch

Expected behavior

OpenSearch should start and export traces via OTLP gRPC to the configured endpoint as documented.

Additional Details

OpenSearch Version

Tested on both 2.17.1 and 2.19.1 - same error.

Operating System

Linux (Docker container using opensearchproject/opensearch:2.19.1)

Additional context

• The documentation states this setting should work: https://docs.opensearch.org/latest/observing-your-data/trace/distributed-tracing#exporters
• Related issue: #13323 (also describes inability to configure OTLP export)
• Without this setting, users cannot send OpenSearch traces to external collectors like Jaeger or any OTLP-compatible backend
• The OTEL_EXPORTER_OTLP_ENDPOINT environment variable is also not respected