Null safety during failing tests (BuildTriggerTest.testMavenBuildTrigger in this case).

java.lang.NullPointerException
	at hudson.model.Job.getBuildDir(Job.java:790)
	at hudson.model.Run.getRootDir(Run.java:993)
	at hudson.model.Run.getLogFile(Run.java:1306)
	at hudson.model.Run.execute(Run.java:1664)
	at hudson.maven.MavenBuild.access$900(MavenBuild.java:94)
	at hudson.maven.MavenBuild$ProxyImpl2.close(MavenBuild.java:636)
	at hudson.maven.AbstractMavenBuilder.end(AbstractMavenBuilder.java:106)
	at hudson.maven.MavenModuleSetBuild$MavenModuleSetBuildExecution.doRun(MavenModuleSetBuild.java:839)
	at hudson.model.AbstractBuild$AbstractBuildExecution.run(AbstractBuild.java:523)
	at hudson.model.Run.execute(Run.java:1688)
	at hudson.maven.MavenModuleSetBuild.run(MavenModuleSetBuild.java:519)
	at hudson.model.ResourceController.execute(ResourceController.java:88)
	at hudson.model.Executor.run(Executor.java:231)
java.lang.NullPointerException
	at hudson.model.BuildStepListener.all(BuildStepListener.java:31)
	at hudson.model.AbstractBuild$AbstractBuildExecution.perform(AbstractBuild.java:739)
	at hudson.model.AbstractBuild$AbstractBuildExecution.performAllBuildSteps(AbstractBuild.java:714)
	at hudson.maven.MavenModuleSetBuild$MavenModuleSetBuildExecution.cleanUp(MavenModuleSetBuild.java:1054)
	at hudson.model.Run.execute(Run.java:1733)
	at hudson.maven.MavenModuleSetBuild.run(MavenModuleSetBuild.java:519)
	at hudson.model.ResourceController.execute(ResourceController.java:88)
	at hudson.model.Executor.run(Executor.java:231)

core/src/main/java/hudson/model/BuildStepListener.java

@@ -5,8 +5,6 @@ import hudson.ExtensionPoint;
 import hudson.tasks.BuildStep;
 import jenkins.model.Jenkins;
 
-import java.util.List;
-
 /**
  * Receives events that happen as a build executes {@link BuildStep}s.
  * @author <a href="mailto:nicolas.deloof@gmail.com">Nicolas De Loof</a>
@@ -28,6 +26,7 @@ public abstract class BuildStepListener implements ExtensionPoint {
      * Returns all the registered {@link BuildStepListener}s.
      */
     public static ExtensionList<BuildStepListener> all() {
+        // TODO should have a null-safe version when Jenkins.getInstance() is null; would require changes in ExtensionList
         return Jenkins.getInstance().getExtensionList(BuildStepListener.class);
     }
 }

core/src/main/java/hudson/model/Job.java

@@ -787,7 +787,11 @@ public abstract class Job<JobT extends Job<JobT, RunT>, RunT extends Run<JobT, R
      * @see RunMap
      */
     public File getBuildDir() {
-        return Jenkins.getInstance().getBuildDirFor(this);
+        Jenkins j = Jenkins.getInstance();
+        if (j == null) {
+            return new File(getRootDir(), "builds");
+        }
+        return j.getBuildDirFor(this);
     }
 
     /**

core/src/main/java/jenkins/model/Jenkins.java

@@ -701,7 +701,12 @@ public class Jenkins extends AbstractCIBase implements DirectlyModifiableTopLeve
         }
     };
 
+    /**
+     * Gets the Jenkins singleton.
+     * @return the instance, or null if Jenkins has not been started, or was already shut down
+     */
     @CLIResolver
+    @CheckForNull
     public static Jenkins getInstance() {
         return HOLDER.getInstance();
     }