Cut 1.15.0/1.15.1 headings in CHANGELOG and merge duplicate subsections

[dmccoystephenson]

Summary

• The entries that shipped in 1.15.0 are moved under a new ## [1.15.0] – 2026-09-19 heading. The set of entries was taken from CHANGELOG.md at the v1.15.0 tag (release commit 21132ed, chore: release 1.15.0 #343), and the date is that commit's date. Every bullet there matches a bullet that was under [Unreleased] on main.
• A ## [1.15.1] – 2026-09-26 heading is added. git diff v1.15.0 v1.15.1 touches only the <version> in pom.xml, so the entry states that only the version number changed.
• Only the three entries added after v1.15.1 stay under [Unreleased]: the test suite, trace-client 0.3.0 and trace-client 0.4.0.
• The duplicate ### Added / ### Changed / ### Fixed subsections are merged and ordered Added → Changed → Fixed. The duplicate ### Changed in [2.0.0-SNAPSHOT-8-8-2026] is merged the same way.
• One wording change: the config-defaults entry referred to a divergence "fixed above". It now says "fixed below", because the Fixed subsection comes after Changed in the new order.

No bullet text was removed or rewritten apart from that wording change. A script compared the bullets before and after and found no other difference.

Not changed: [2.0.0-SNAPSHOT-8-8-2026] stays where it is in the file. How that snapshot line should be ordered against the 1.15.x releases is the maintainer's call, as the issue notes. It is recorded here as an open question and is not decided by this PR.

Test plan

• Bullet-set comparison against HEAD:CHANGELOG.md and v1.15.0:CHANGELOG.md (script-verified)
• grep -n '^##' CHANGELOG.md shows no duplicate subsection under any release heading
• CI build green (docs-only change; no source files touched)

Closes #346

Other open issues were not picked up this cycle. #342 is done on the external download listings, not in this repository. #303, #304, #305, #302, #292, #283, #282, #281, #280, #265 and #264 are feature requests or larger work, beyond a documentation-sized cycle.

This PR description was drafted during a Gardener session (https://github.com/Stephenson-Software/gardener).

🤖 Generated with Claude Code

---

drafted by Claude on behalf of Daniel Stephenson

[dmccoystephenson]

Self-review rubric (head of feature/changelog-release-headings):

• Scope: PASS — only CHANGELOG.md is modified, and every hunk moves a bullet, adds a release heading, or merges a subsection for CHANGELOG.md has no [1.15.0] heading and duplicate subsections under [Unreleased] #346.
• Tests-new: PASS (not applicable) — no code was added. The repo's test suite does not cover CHANGELOG.md.
• Tests-fix: not applicable — documentation-only change with no behavioural fix. The equivalent empirical check was a scripted comparison of the bullet sets. It confirmed that the [1.15.0] bullets match v1.15.0:CHANGELOG.md exactly (apart from the one intended wording change) and that no bullet from HEAD:CHANGELOG.md was lost.
• Sibling structure: PASS — the new headings use the existing ## [x.y.z] – YYYY-MM-DD form. Subsection order follows Keep a Changelog (Added, Changed, Fixed).
• Sibling renames: not applicable.
• Docs: PASS — README / USER_GUIDE / COMMANDS / CONFIG / plugin.yml are not affected by a changelog restructure.
• Issue resolution: PARTIAL, judgment call flagged — CHANGELOG.md has no [1.15.0] heading and duplicate subsections under [Unreleased] #346 lists three items. Items 1 and 2 (cut [1.15.0], merge duplicates) are done. Item 3 (confirm the ordering of 2.0.0-SNAPSHOT-8-8-2026 relative to 1.15.x) is a maintainer decision and was deliberately left unchanged. The issue itself frames all three as "for the maintainer to decide", and items 1–2 turned out to be settled by the release tags. Closes #346 is kept on that basis. If the ordering question should stay tracked, a follow-up issue is appropriate.
• CI: PASS — build is green on the PR head (run 36698384380).
• JDK 8 compatibility: not applicable — no Java source changed.
• Permissions: not applicable — plugin.yml is untouched.

Out-of-diff observation: CHANGELOG.md:24 — the 1.15.0 date (2026-09-19) is the commit date of the release commit 21132ed (#343), not a GitHub Release publish date. Release listing was not queryable in this session.

This review was drafted during a Gardener session (https://github.com/Stephenson-Software/gardener).

---

drafted by Claude on behalf of Daniel Stephenson