Enable jvm.gc.cause attribute by default

[somiljain2006]

Fixes #16063

Change runtime telemetry to default capture_gc_cause to true, while preserving the deprecated configuration option for
backward compatibility. Update the documentation and Spring configuration metadata, and add tests covering the new default behavior and explicit opt-out.

[linux-foundation-easycla]

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• ✅ login: somiljain2006 / name: somiljain2006 (ee771a3, fe175d7)

[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

Updates runtime-telemetry configuration so GC cause capture is enabled by default, with documentation and tests reflecting the new default and deprecation behavior when disabling it.

Changes:

• Switched capture-gc-cause default from false to true in Spring Boot metadata and runtime-telemetry docs.
• Updated runtime-telemetry internal config default to true and adjusted the deprecation warning to trigger when disabling.
• Added unit tests to validate the new default and the ability to disable.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 4 comments.

File	Description
instrumentation/spring/spring-boot-autoconfigure/src/main/resources/META-INF/additional-spring-configuration-metadata.json	Updates Spring Boot config metadata default for capture-gc-cause to true.
instrumentation/runtime-telemetry/library/src/main/java/io/opentelemetry/instrumentation/runtimetelemetry/internal/Internal.java	Changes config default to enabled and updates warning behavior/message when disabling.
instrumentation/runtime-telemetry/README.md	Documents the new default value for capture-gc-cause.
instrumentation/runtime-telemetry/library/src/test/java/io/opentelemetry/instrumentation/runtimetelemetry/RuntimeTelemetryTest.java	Adds tests validating default behavior and disabling behavior.

[somiljain2006]

@trask I have done the required changes, can you review them?