I finally found out that the use of WS-Addressing is not picked up from the policy.
I got rid of the problem by adding the @Addressing annotation to the Provider implementation:
@WebServiceProvider(serviceName = "purchaseorderprocessin3",
portName = "SalesOrderProcessingOrderingOutPort",
targetNamespace = "http://sap.com/xi/AP/CRM/Global",
wsdlLocation = "WEB-INF/wsdl/SalesOrderProcessingOrderingOut.wsdl")
@ServiceMode(value = Service.Mode.PAYLOAD)
@Addressing(required=true)
public class SalesOrderProcessingOrderingOutImpl implements Provider<Source> {
...
}
More details here: http://download.oracle.com/javase/6/docs/api/javax/xml/ws/soap/AddressingFeature.html