code: public void useXopAttachmentServiceWithProxy() throws Exception {
  
          final String serviceURI = "http://localhost:" + port + "/services/attachments";
          
          XopAttachmentService proxy = JAXRSClientFactory.create(serviceURI, 
                                                                 XopAttachmentService.class);
          
          XopBean xop = createXopBean();
          
          System.out.println();
          System.out.println("Posting a XOP attachment with a proxy");
                  
          XopBean xopResponse = proxy.echoXopAttachment(xop);
          
          verifyXopResponse(xop, xopResponse);
      }
docs: Writes and reads the XOP attachment using a CXF JAX-RS Proxy
  The proxy automatically sets the "mtom-enabled" property by checking
  the CXF EndpointProperty set on the XopAttachment interface.
  
  @throws Exception