Publish milestones on Maven Central

This commit adapts the release pipeline to publish milestones on both
our milestone repository and Maven Central. To make sure users can
consume everything without the need of an extra repository, this commit
also publishes the Gradle plugin to the Gradle Plugin Portal.

Closes gh-46024

Author: snicoll

.github/workflows/release-milestone.yml

@@ -50,11 +50,28 @@ jobs:
     with:
       staging: true
       version: ${{ needs.build-and-stage-release.outputs.version }}
+  sync-to-maven-central:
+    name: Sync to Maven Central
+    if: ${{ !vars.COMMERCIAL }}
+    needs:
+      - build-and-stage-release
+      - verify
+    runs-on: ${{ vars.UBUNTU_SMALL || 'ubuntu-latest' }}
+    steps:
+      - name: Check Out Code
+        uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
+      - name: Sync to Maven Central
+        uses: ./.github/actions/sync-to-maven-central
+        with:
+          central-token-password: ${{ secrets.CENTRAL_TOKEN_PASSWORD }}
+          central-token-username: ${{ secrets.CENTRAL_TOKEN_USERNAME }}
+          jfrog-cli-config-token: ${{ secrets.JF_ARTIFACTORY_SPRING }}
+          spring-boot-version: ${{ needs.build-and-stage-release.outputs.version }}
   promote-release:
     name: Promote Release
     needs:
       - build-and-stage-release
-      - verify
+      - sync-to-maven-central
     runs-on: ${{ vars.UBUNTU_SMALL || 'ubuntu-latest' }}
     steps:
       - name: Set up JFrog CLI
@@ -63,11 +80,28 @@ jobs:
           JF_ENV_SPRING: ${{ secrets.JF_ARTIFACTORY_SPRING }}
       - name: Promote build
         run: jfrog rt build-promote ${{ format('spring-boot-{0}', needs.build-and-stage-release.outputs.version)}} ${{ github.run_number }} libs-milestone-local
+  publish-gradle-plugin:
+    name: Publish Gradle Plugin
+    if: ${{ !vars.COMMERCIAL }}
+    needs:
+      - build-and-stage-release
+      - sync-to-maven-central
+    runs-on: ${{ vars.UBUNTU_SMALL || 'ubuntu-latest' }}
+    steps:
+      - name: Check Out Code
+        uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
+      - name: Publish
+        uses: ./.github/actions/publish-gradle-plugin
+        with:
+          gradle-plugin-publish-key: ${{ secrets.GRADLE_PLUGIN_PUBLISH_KEY }}
+          gradle-plugin-publish-secret: ${{ secrets.GRADLE_PLUGIN_PUBLISH_SECRET }}
+          jfrog-cli-config-token: ${{ secrets.JF_ARTIFACTORY_SPRING }}
+          plugin-version: ${{ needs.build-and-stage-release.outputs.version }}
   trigger-docs-build:
     name: Trigger Docs Build
     needs:
       - build-and-stage-release
-      - verify
+      - sync-to-maven-central
     permissions:
       actions: write
     runs-on: ubuntu-latest
@@ -81,6 +115,7 @@ jobs:
     needs:
       - build-and-stage-release
       - promote-release
+      - publish-gradle-plugin
       - trigger-docs-build
     runs-on: ${{ vars.UBUNTU_SMALL || 'ubuntu-latest' }}
     steps: