[JENKINS-20609] test case

core/src/main/java/hudson/WebAppMain.java

@@ -72,7 +72,7 @@ import static java.util.logging.Level.*;
  *
  * @author Kohsuke Kawaguchi
  */
-public final class WebAppMain implements ServletContextListener {
+public class WebAppMain implements ServletContextListener {
     private final RingBufferLogHandler handler = new RingBufferLogHandler() {
         @Override public synchronized void publish(LogRecord record) {
             if (record.getLevel().intValue() >= Level.INFO.intValue()) {
@@ -251,6 +251,10 @@ public final class WebAppMain implements ServletContextListener {
         }
     }
 
+    public void joinInit() throws InterruptedException {
+        initThread.join();
+    }
+
     /**
      * To assist boot failure script, record the number of boot attempts.
      * This file gets deleted in case of successful boot.