chore(ci): trigger daily CI in v3.x-java branch

.github/workflows/daily_ci_java_3x.yml

@@ -0,0 +1,48 @@
+name: Daily CI (v3.x-java)
+
+on:
+  schedule:
+    - cron: "00 13 * * 1-5"
+  pull_request:
+    paths: .github/workflows/daily_ci_java_3x.yml
+
+permissions:
+  contents: read
+  id-token: write
+
+jobs:
+  trigger:
+    permissions:
+      actions: write
+      contents: read
+    runs-on: ubuntu-latest
+    steps:
+      - name: Fail after end of support
+        run: |
+          CUTOFF="2026-08-01"
+          NOW=$(date -u +%Y-%m-%d)
+          if [[ "$NOW" > "$CUTOFF" || "$NOW" == "$CUTOFF" ]]; then
+            echo "CI disabled as v3.x is end of support after $CUTOFF"
+            exit 1
+          fi
+      - uses: actions/github-script@v7
+        with:
+          script: |
+            await github.rest.actions.createWorkflowDispatch({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              workflow_id: 'daily_ci.yml',
+              ref: 'v3.x-Java'
+            });
+  notify:
+    permissions:
+      contents: read
+      pull-requests: write
+      id-token: write
+    needs: [trigger]
+    if: ${{ failure() && github.event_name == 'schedule'}}
+    uses: aws/aws-cryptographic-material-providers-library/.github/workflows/slack-notification.yml@main
+    with:
+      message: "Failed to trigger Daily CI for branch v3.x-Java (see daily_ci_java_3x.yml on main) on `${{ github.repository }}`. View run: ${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}"
+    secrets:
+      SLACK_WEBHOOK_URL: ${{ secrets.SLACK_WEBHOOK_URL_CI }}