PMD implementation in GitHub action (#294)

* PMD implementation in GitHub action

* Update build.yml

.github/workflows/build.yml

@@ -1,9 +1,23 @@
 ---
 name: build
 
-on: push
+on:
+  push:
+  pull_request:
 
 jobs:
+  pmd_scan:
+    name: "PMD Scan"
+    runs-on: ubuntu-latest
+    if: >
+      github.event_name == 'pull_request' &&
+      !contains(github.event.head_commit.message, '[skip pmd]') &&
+      !contains(github.event.head_commit.message, '[force]')
+    steps:
+      - uses: Alfresco/ya-pmd-scan@v2.0.2
+        with:
+          fail-on-new-issues: "false"
+          create-github-annotations: "false"
   build:
     runs-on: ubuntu-latest