ci: Add Maven Central release workflow with GitHub Release

.github/actions/jdk-setup/action.yml

@@ -1,10 +1,46 @@
 name: "JDK Setup"
+description: "Set up Temurin JDK 21 with Maven dependency caching"
+inputs:
+  server-id:
+    description: "Maven settings.xml server id for Maven Central authentication."
+    required: false
+    default: ''
+  server-username:
+    description: "Environment variable name for the Maven Central username."
+    required: false
+    default: ''
+  server-password:
+    description: "Environment variable name for the Maven Central password."
+    required: false
+    default: ''
+  gpg-private-key:
+    description: "GPG private key to import for artifact signing."
+    required: false
+    default: ''
+  gpg-passphrase:
+    description: "Environment variable name for the GPG passphrase."
+    required: false
+    default: ''
 runs:
   using: "composite"
   steps:
-    - name: Set up JDK 8
-      uses: actions/setup-java@v4
+    - name: Set up JDK 21
+      if: ${{ inputs.server-id == '' }}
+      uses: actions/setup-java@v5
       with:
         java-version: '21'
         distribution: 'temurin'
         cache: maven
+
+    - name: Set up JDK 21 with Maven Central credentials
+      if: ${{ inputs.server-id != '' }}
+      uses: actions/setup-java@v5
+      with:
+        java-version: '21'
+        distribution: 'temurin'
+        cache: maven
+        server-id: ${{ inputs.server-id }}
+        server-username: ${{ inputs.server-username }}
+        server-password: ${{ inputs.server-password }}
+        gpg-private-key: ${{ inputs.gpg-private-key }}
+        gpg-passphrase: ${{ inputs.gpg-passphrase }}

.github/workflows/release.yml

@@ -0,0 +1,83 @@
+name: Release to Maven Central
+
+on:
+  push:
+    tags: ['plugin-*'] # release tags are prefixed with "plugin-"
+
+permissions:
+  contents: read
+
+concurrency:
+  group: release-deploy
+  cancel-in-progress: false
+
+env:
+  MAVEN_COMMAND: ./mvnw
+  MAVEN_CLI_COMMON: "-e -B"
+
+jobs:
+  release:
+    runs-on: ubuntu-latest
+    timeout-minutes: 120
+    environment: release
+    outputs:
+      version: ${{ steps.resolve.outputs.version }}
+    steps:
+      - uses: actions/checkout@v7
+        with:
+          persist-credentials: false
+
+      - uses: ./.github/actions/jdk-setup
+        with:
+          server-id: central-publish
+          server-username: CENTRAL_USERNAME
+          server-password: CENTRAL_TOKEN
+          gpg-private-key: ${{ secrets.GPG_PRIVATE_KEY }}
+          gpg-passphrase: MAVEN_GPG_PASSPHRASE
+
+      # Guard against a mistyped tag releasing the wrong version: the POM is the
+      # source of truth for what gets deployed, so the tag must encode exactly that
+      # version. The resolved version also titles the GitHub Release below.
+      - name: Verify tag matches project version
+        id: resolve
+        env:
+          TAG: ${{ github.ref_name }}
+        run: |
+          version="$(${{ env.MAVEN_COMMAND }} help:evaluate -Dexpression=project.version -q -DforceStdout)"
+          expected="plugin-${version}"
+          if [ "$TAG" != "$expected" ]; then
+            echo "::error::Tag '$TAG' does not match project version (expected '$expected'). Refusing to release."
+            exit 1
+          fi
+          echo "version=${version}" >> "$GITHUB_OUTPUT"
+
+      # Tests already ran during release:prepare.
+      - name: Deploy release to Maven Central
+        env:
+          CENTRAL_USERNAME: ${{ secrets.CENTRAL_USERNAME }}
+          CENTRAL_TOKEN: ${{ secrets.CENTRAL_TOKEN }}
+          MAVEN_GPG_PASSPHRASE: ${{ secrets.GPG_PASSPHRASE }}
+        run: ${{ env.MAVEN_COMMAND }} ${{ env.MAVEN_CLI_COMMON }} deploy -Prelease -DskipTests
+
+  # Publish a GitHub Release for the tag once the Central deploy succeeds. Notes are
+  # auto-generated by the GitHub Release Notes API from merged PRs/commits since the
+  # previous tag. Isolated from the deploy job so contents:write is not granted while
+  # GPG keys and Central credentials are in scope.
+  github-release:
+    needs: release
+    runs-on: ubuntu-latest
+    timeout-minutes: 10
+    permissions:
+      contents: write # required to create the GitHub Release
+    steps:
+      - name: Create GitHub Release
+        env:
+          GH_TOKEN: ${{ github.token }}
+          TAG: ${{ github.ref_name }} # via env to avoid script injection
+          VERSION: ${{ needs.release.outputs.version }}
+        run: |
+          gh release create "$TAG" \
+            --repo "${{ github.repository }}" \
+            --title "$VERSION" \
+            --generate-notes \
+            --verify-tag