only trigger via pull_request_target

debug event with toJSON function
fix yaml
use caching integrated in setup-java

.github/workflows/maven.yml

@@ -5,12 +5,11 @@ on:
   push:
     branches:
     - master
-  # for PRs from forked repos
+  # for PRs from forked repos and non forked repos
   # in order to write status info to the PR we require write repository token (https://github.blog/2020-08-03-github-actions-improvements-for-fork-and-pull-request-workflows/)
   pull_request_target:
-    types: [opened, synchronize, reopened]
-  # for PRs from ACS AEM Commons repository directly (non-forked repo)
-  pull_request:
+    branches:
+    - master
     types: [opened, synchronize, reopened]
 
 # restrict privileges except for setting commit status, adding PR comments and writing statuses
@@ -45,9 +44,10 @@ jobs:
 
     steps:
       - name: Debug Event
+        env:
+          GH_EVENT: ${{ toJSON(github.event) }}
         shell: bash
-        run: 
-          echo "Event that triggered action: ${{ github.event }}" 
+        run: echo "Event that triggered the action $GH_EVENT"
       - name: Checkout
         uses: actions/checkout@v2
         # always act on the modified source code (even for event pull_request_target)
@@ -57,17 +57,10 @@ jobs:
           # no additional git operations after checkout triggered in workflow, no need to store credentials
           persist-credentials: false
 
-      - name: Set up cache for ~/.m2/repository
-        uses: actions/cache@v2
-        with:
-          path: ~/.m2/repository
-          key: maven-${{ matrix.os }}-${{ hashFiles('**/pom.xml') }}
-          restore-keys: |
-            maven-${{ matrix.os }}-
-
       - name: Set up JDK
         uses: actions/setup-java@v2
         with:
+          cache: 'maven'
           distribution: 'adopt'
           java-version: ${{ matrix.jdk }}
           # generate settings.xml with the correct values