KieServicesConfiguration config = KieServicesFactory.newRestConfiguration(
"http://localhost:8230/kie-server/services/rest/server", "kieserver", "kieserver1!");
config.setMarshallingFormat(MarshallingFormat.XSTREAM);
KieServicesClient client = KieServicesFactory.newKieServicesClient(config);

System.out.println(xStreamXml);

// "ListenerReproducer" is the name of the Container
ServiceResponse<String> response = client.executeCommands("mortgages", xStreamXml);

THE CODE CAN NOT WORK IN 6.3 FINAL,but it can work in 6.3 rc2

because the container's POST URI is changed

http://localhost:8230/kie-server/services/rest/server/containers/instances/mortgages

there is a "instances" behind the containers