Introduce format check in GitHub action

The check is always run before the build. The TCK is still run if the
formatting check fails.
diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index c31b939..7b631ab 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -27,8 +27,23 @@
   pull_request:
 
 jobs:
+  format-check:
+    name: Check Code Formatting
+    continue-on-error: true
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v2
+      with:
+        fetch-depth: 1
+    - name: Check Format
+      run: |
+        mvn -Pverify-format clean compile
+      shell: 'bash'
+
   build-jdo:
     name: Build JDO & Run TCK
+    needs: format-check
     runs-on: ubuntu-latest
     strategy:
       matrix:
diff --git a/README.md b/README.md
index d0ef390..facd6a1 100644
--- a/README.md
+++ b/README.md
@@ -183,3 +183,7 @@
 * `format` reformats the project's Java files.
 
         mvn -Pformat clean compile
+
+#### GitHub Action Integration
+
+The formatting of the code is checked automatically through the GitHub actions for every PR and/or push on master.
diff --git a/parent-pom/pom.xml b/parent-pom/pom.xml
index 3197f6c..6f25ea3 100644
--- a/parent-pom/pom.xml
+++ b/parent-pom/pom.xml
@@ -436,7 +436,7 @@
                         <configuration>
                             <displayLimit>1000</displayLimit>
                             <verbose>true</verbose>
-                            <failOnError>false</failOnError>
+                            <failOnError>true</failOnError>
                         </configuration>
                         <executions>
                             <execution>