[FIXED JENKINS-10375] Maven build error if headless option is checked and MAVEN_OPTS are empty

changelog.html

@@ -63,6 +63,9 @@ Upcoming changes</a>
   <li class=bug>
     Fixed an occasional NPE when running Maven jobs 
     (<a href="https://issues.jenkins-ci.org/browse/JENKINS-9822">issue 9822</a>)
+  <li class=bug>
+    Fixed Maven build error if headless option is set and MAVEN_OPTS empty
+    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-10375">issue 10375</a>)
 </ul>
 </div><!--=TRUNK-END=-->
 

maven-plugin/src/main/java/hudson/maven/AbstractMavenProcessFactory.java

@@ -276,7 +276,11 @@ public abstract class AbstractMavenProcessFactory
 
         if (mms.runHeadless()) {
             // Configure headless process
-            mavenOpts += " -Djava.awt.headless=true";
+            if (mavenOpts == null) {
+                mavenOpts = "-Djava.awt.headless=true";
+            } else {
+                mavenOpts += " -Djava.awt.headless=true";
+            }
         } else {
             if (Platform.isDarwin()) {
                 // Would be cool to replace the generic Java icon with jenkins logo, but requires