[zhongkechen]

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Issue Link, if available

Release preparation follow-up to #813 for the draft v3.0.0 release. Incorporates the migration implications of #817, #820, and #821.

Description

The migration guide still describes the factory release as 3.0.0-SNAPSHOT and omits changes consumers need for the proposed 3.0.0 artifacts. Document coordinated Core, Testing, and OTel versions, a Maven dependency example, provider/layer rebuilding, and the concrete factory-method compatibility check. Java's OTel artifact uses 3.0.0; Python and JavaScript version their OTel packages separately.

Document the release decision that the Telemetry Exporter becomes a stable public API in 3.0.0, with migration guidance for consumers of earlier preview builds. Its migration section covers the factory return type, registration recompilation, Lambda JSON log envelope, fixed-width millisecond UTC timestamps, invocation-scoped emittedAt ordering, and optional error causes. The OTel section explains Java-agent sampler verification, chained-invoke propagation and fallback, and deterministic propagation during replay/retry.

Organize the guide around dependency upgrades, registration changes, resource ownership, lifecycle behavior, and validation. Preserve existing API examples and the documented limits for stale directly registered providers and non-cooperative cleanup. Expand the affected-code searches and validation steps for the merged tracing and exporter changes.

The guide continues to describe a proposed release. The draft release notes link to this guide's updated revision. Before publication, align the exporter's source annotations and README with the stable 3.0.0 API decision; this documentation PR does not change those files.

Demo/Screenshots

Not applicable; the Markdown guide is included in the diff and its rendered headings and links were checked locally.

Checklist

• I have filled out every section of the PR template
• I have thoroughly tested this change

Testing

Unit Tests

No runtime unit tests added or run for this documentation-only change. Verified the documented behavior against current SDK source and the OTel/exporter references. The repository-wide Java 17 offline Spotless check passed.

Integration Tests

No runtime behavior changed. Rendered the Markdown and checked all 14 links, including local targets and anchors. Parsed the Maven example as XML and verified its coordinated 3.0.0 dependencies. Hidden-character and git diff --check checks passed.

Examples

All 17 fenced blocks are retained. Existing Java, XML, and diagnostic examples are unchanged by the release-alignment update; affected-code searches now include tracing configuration and telemetry consumers. Publication is still required before consumers can resolve the proposed release coordinates.

[github-actions]

Codex AI review

No actionable findings. The prior stability-contract concern is resolved in the base revision. This documentation-only review was static; runtime and cloud migration paths were not exercised.

Reviewed commit 7641df9e3ae8ac53f1b1d2fad1c2b788cfb7849f. Workflow run