#fixed code
                             protected void registerWithLongPollingServer(AsyncBrowserSession bs) {
		JUnitSession.getInstance().getDependency(HttpLongPollingServer.class).registerBrowserSession(bs);
	}
#vulnerable code 
                             protected void registerWithLongPollingServer(AsyncBrowserSession bs) {
		JUnitSession.getInstance().getDependency(AsyncServerSession.class).registerBrowserSession(bs);
	} 
                            #location 2 
                            #vulnerability type NULL_DEREFERENCE