Scope demo build step to demo changes

Author: shai-almog

.github/workflows/developer-guide-docs.yml

@@ -23,19 +23,30 @@ jobs:
       - name: Check out repository
         uses: actions/checkout@v4
 
+      - name: Determine changed components
+        id: changes
+        if: github.event_name == 'pull_request'
+        uses: dorny/paths-filter@v3
+        with:
+          filters: |
+            demos:
+              - 'docs/demos/**'
+            docs:
+              - 'docs/developer-guide/**'
+
       - name: Set up Java
         uses: actions/setup-java@v4
         with:
           distribution: 'temurin'
           java-version: '11'
 
       - name: Build Codename One demos
+        if: github.event_name != 'pull_request' || steps.changes.outputs.demos == 'true'
         run: |
           set -euo pipefail
           mkdir -p "$HOME/.codenameone"
           touch "$HOME/.codenameone/guibuilder.jar"
-          printf 'Manifest-Version: 1.0\n' > /tmp/cn1-manifest.mf
-          jar cfm "$HOME/.codenameone/CodeNameOneBuildClient.jar" /tmp/cn1-manifest.mf
+          cp maven/CodeNameOneBuildClient.jar "$HOME/.codenameone/CodeNameOneBuildClient.jar"
           xvfb-run -a mvn -B -ntp -Dgenerate-gui-sources-done=true -pl common -am -f docs/demos/pom.xml test
 
       - name: Determine publication metadata
@@ -103,6 +114,7 @@ jobs:
           gem install --no-document asciidoctor asciidoctor-pdf
 
       - name: Build Developer Guide HTML and PDF
+        if: github.event_name != 'pull_request' || steps.changes.outputs.docs == 'true' || steps.changes.outputs.demos == 'true'
         run: |
           set -euo pipefail
           OUTPUT_ROOT="build/developer-guide"