fix(docker): resolve toolchain versions at build time instead of pinning

[GordonBeeming]

Problem

The post-merge Build and Publish run on main failed on Build java (run 28349443241): the Eclipse JDT language server download 404'd. It was pinned to a milestone URL (JDTLS_VERSION=1.43.0), and Eclipse deletes old milestones, so the pin was guaranteed to rot.

The same hard-pinned pattern was used for Go, Maven, Gradle, and PlantUML. Those don't 404 (their hosts keep archives), but they silently go stale and need manual bump PRs.

Fix

.NET already avoids this — dotnet{8,9,10}.Dockerfile resolve the latest SDK at build time via dotnet-install.sh --channel. This applies the same build-time-latest, optionally-pinnable pattern to the remaining toolchains, so generated Dockerfiles no longer carry version numbers and the rot can't recur.

Tool	Resolve mechanism (verified live)
JDTLS	stable snapshots/jdt-language-server-latest.tar.gz symlink
Go	go.dev/VERSION?m=text
Gradle	services.gradle.org/versions/current
PlantUML	GitHub latest-release unversioned asset
Maven	latest stable 3.9.x from the dlcdn.apache.org listing — not maven-metadata <release>, which is currently 4.0.0-rc-5 (a release candidate)

Each tool keeps an optional pin ARG (GOLANG_VERSION, MAVEN_VERSION, GRADLE_VERSION, JDTLS_URL, PLANTUML_URL) defaulting to "resolve latest", mirroring DOTNET_SDK_N_VERSION. Every resolve step guards against an empty result (test -n) so a failed lookup fails the build loudly instead of producing a broken image.

Notes

• Gradle jumps 8.12 → 9.x on first build. These are dev/agent images and Gradle is backward-tolerant; pin via GRADLE_VERSION build-arg if any image needs to stay on 8.x.
• Maven stays on stable 3.9.x by design; the listing filter excludes the Maven 4 RCs. Widen it deliberately when Maven 4 GAs.
• Reproducibility tradeoff is accepted: builds days apart can pull different tool versions; the pin ARGs are the escape hatch.

Test plan

• pwsh docker/generate-dockerfiles.ps1 regenerates clean; only Dockerfile.java + Dockerfile.golang change among main-tracked generated files (the snippets feed only those two images on main).
• Every resolve URL confirmed live (200 / valid JSON); Maven filter yields 3.9.16, not the 4.0.0-rc-5 RC.
• Real proof is the Build * image jobs in this PR's publish pipeline — each snippet ends with a RUN … --version smoke check (go version; java --version && mvn --version && gradle --version && plantuml -version), so a bad resolve fails the image build. Green Build java + Build golang is the signal.

🤖 Generated with Claude Code

[gemini-code-assist]

Code Review

This pull request updates the Dockerfiles and snippets for Go and Java to dynamically resolve the latest stable versions of Go, Maven, Gradle, PlantUML, and Eclipse JDTLS at image-build time, while still allowing version pinning via build arguments. The review feedback suggests several improvements to make the build process more robust and consistent: using the Apache archive URL instead of the CDN mirror for Maven downloads to prevent 404 errors when pinning older versions, stripping the leading 'go' prefix from the Go version for better backward compatibility, and simplifying the Gradle version resolution logic using shell parameter expansion instead of an if/then/fi block.

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[Copilot]

Pull request overview

Updates Docker build snippets (and regenerated Dockerfiles) to resolve several toolchain versions at build time rather than hard-pinning versions that can go stale (notably Eclipse JDTLS milestone URLs).

Changes:

• Switch JDTLS install to use the stable jdt-language-server-latest.tar.gz snapshots symlink (with an optional JDTLS_URL pin).
• Resolve Maven (stable 3.9.x), Gradle (current release), PlantUML (GitHub latest asset), and Go (go.dev current) at image build time, with optional pin build args.
• Regenerate docker/generated/* to reflect updated snippets.

Reviewed changes

Copilot reviewed 3 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
docker/snippets/lsp-java.Dockerfile	Moves JDTLS download from pinned milestone tarball to the snapshots “latest” symlink with optional URL pin.
docker/snippets/java.Dockerfile	Resolves Maven/Gradle/PlantUML at build time and updates install logic accordingly.
docker/snippets/golang.Dockerfile	Resolves Go version at build time via go.dev/VERSION?m=text with optional pin arg.
docker/generated/Dockerfile.java	Regenerated output reflecting updated Java snippet resolution logic and JDTLS URL arg.
docker/generated/Dockerfile.golang	Regenerated output reflecting updated Go snippet resolution logic.

[chatgpt-codex-connector]

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