Use Xvfb for testing

Jenkinsfile

@@ -12,6 +12,7 @@ pipeline {
         GPG_OWNER_TRUST = credentials('8703bbe8-c099-481f-8337-1dce32d51771')
     }
 
+    wrap([$class: 'Xvfb']) {
         stages {
             stage("Import GPG Keys") {
                 when {
@@ -30,11 +31,9 @@ pipeline {
                 }
             }
             stage("Test") {
-            wrap([$class: 'Xvfb']) {
                 steps {
                     sh "mvn test"
                 }
-            }
                 post {
                     success {
                         echo "Generating Test Report..."
@@ -64,6 +63,7 @@ pipeline {
                 }
             }
         }
+    }
 
     post {
         success {