NPE when switching from beta 15 to beta 17

This code was running fine with beta15:
jettyServer = new Server();
SocketConnector connector = new SocketConnector();
connector.setPort(JWebUnitAPITestCase.JETTY_PORT);
jettyServer.setConnectors (new Connector[]{connector});
WebAppContext wah = new WebAppContext();
wah.setServer(jettyServer);
wah.setContextPath(JWebUnitAPITestCase.JETTY_URL);
URL url = this.getClass().getResource("/testcases/");
wah.setWar(url.toString());
jettyServer.addHandler(wah);
jettyServer.start();

But when switching to beta17, I get:
Running net.sourceforge.jwebunit.htmlunit.JWebUnitTest
:INFO: Logging to STDERR via org.mortbay.log.StdErrLog
java.lang.NullPointerException
at org.mortbay.jetty.handler.HandlerCollection.setHandlers(HandlerCollection.java:76)
at org.mortbay.jetty.Server.addHandler(Server.java:460)
at net.sourceforge.jwebunit.tests.util.JettySetup.setUp(JettySetup.java:66)
...

The problem is in Server.java, in method addHandler(Handler handler):
When you call:
HandlerCollection collection=new HandlerCollection();
collection.setHandlers(new Handler[]{getHandler(),handler});

getHandler() return null