Hi. I had the same problem with that example. Try changing in CodeGenerator.java the line "src/main/resources/SimpleService.wsdl" with "file:src/main/resources/SimpleService.wsdl" in the last parameter of WSDLToJava.main function. Re-execute and you will note code changes in SimpleService_Service.java. Now you can execute the Server and then the Client.
It worked for me!! Regards. Alberto Llopis