Allow gc to remove test results from memory in more proper way

maven-plugin/src/main/java/hudson/maven/reporters/SurefireArchiver.java

@@ -24,6 +24,7 @@
 package hudson.maven.reporters;
 
 import hudson.Extension;
+import hudson.Launcher;
 import hudson.Util;
 import hudson.maven.Maven3Builder;
 import hudson.maven.MavenBuild;
@@ -167,6 +168,20 @@ public class SurefireArchiver extends MavenReporter {
         return true;
     }
     
+    @Override
+    public boolean end(MavenBuild build, Launcher launcher, BuildListener listener) throws InterruptedException, IOException {
+        //Discard unneeded test result objects so they can't waste memory
+        for(MavenReporter reporter: build.getProject().getReporters()) {
+            if(reporter instanceof SurefireArchiver) {
+                SurefireArchiver surefireReporter = (SurefireArchiver) reporter;
+                if(surefireReporter.result != null) {
+                    surefireReporter.result = null;
+                }
+            }
+        }    
+        return true;
+    }
+    
     @edu.umd.cs.findbugs.annotations.SuppressWarnings(value="ST_WRITE_TO_STATIC_FROM_INSTANCE_METHOD", justification="It's okay to write to static fields here, as each Maven build is started in its own VM")
     private void markBuildAsSuccess(Throwable mojoError, MavenBuildInformation buildInfo) {
         if(mojoError == null // in the success case we don't get any exception in Maven 3.0.2+; Maven < 3.0.2 returns no exception anyway