private LegacyCommunicationManager createCommunicationManager()
throws Exception {
VaadinServlet servlet = new VaadinServlet();
servlet.init(new MockServletConfig());
VaadinServletService vss = new VaadinServletService(servlet,
new MockDeploymentConfiguration());
servlet.init(new MockServletConfig());
return new LegacyCommunicationManager(
new AlwaysLockedVaadinSession(vss));
}