Send attachments with Axis-generated SOAP client

Question

I have a service that needs some attachments sent with the SOAP request. For this service I generated a client using Maven's axis2-wsdl2code-maven-plugin and Apache Axis2 1.8.0. The generated stub looks pretty much as mentioned in https://axis.apache.org/axis2/java/core/docs/mtom-guide.html#a32 - with the exception that no attachments are sent. It seems as easy as I just need to create a new MessageContext and use addAttachement with data handlers.

Now my problem is that I am using the generated methods, and I see no way from outside to inject a MessageContext or the attachement datahandlers. I also tried to access the MessageContext as mentioned in Accessing the MessageContext but the method

MessageContext.getCurrentMessageContext()

always returns null for me. And even if it didn't I would not be sure how to inject it into the generated method.

How can I add attachments to the generated stub's functionality?

Just for completeness, here is one of the generated operations. You can see it constructs it's own MessageContext.

  public com.example.myservice.ws.access.CreateResponseDocument create(
      com.example.myservice.ws.access.CreateDocument create42) throws java.rmi.RemoteException {

    org.apache.axis2.context.MessageContext _messageContext =
        new org.apache.axis2.context.MessageContext();
    try {
      org.apache.axis2.client.OperationClient _operationClient =
          _serviceClient.createClient(_operations[21].getName());
      _operationClient
          .getOptions()
          .setAction("http://access.ws.myservice.example.com/AproachWebServices/createRequest");
      _operationClient.getOptions().setExceptionToBeThrownOnSOAPFault(true);

      addPropertyToOperationClient(
          _operationClient,
          org.apache.axis2.description.WSDL2Constants.ATTR_WHTTP_QUERY_PARAMETER_SEPARATOR,
          "&");

      // create SOAP envelope with that payload
      org.apache.axiom.soap.SOAPEnvelope env = null;

      env =
          toEnvelope(
              getFactory(_operationClient.getOptions().getSoapVersionURI()),
              create42,
              optimizeContent(
                  new javax.xml.namespace.QName(
                      "http://access.ws.myservice.example.com", "create")),
              new javax.xml.namespace.QName("http://access.ws.myservice.example.com", "create"));

      // adding SOAP soap_headers
      _serviceClient.addHeadersToEnvelope(env);
      // set the message context with that soap envelope
      _messageContext.setEnvelope(env);

      // add the message contxt to the operation client
      _operationClient.addMessageContext(_messageContext);

      // execute the operation client
      _operationClient.execute(true);

      org.apache.axis2.context.MessageContext _returnMessageContext =
          _operationClient.getMessageContext(
              org.apache.axis2.wsdl.WSDLConstants.MESSAGE_LABEL_IN_VALUE);
      org.apache.axiom.soap.SOAPEnvelope _returnEnv = _returnMessageContext.getEnvelope();
      _returnEnv.buildWithAttachments();

      java.lang.Object object =
          fromOM(
              _returnEnv.getBody().getFirstElement(),
              com.example.myservice.ws.access.CreateResponseDocument.class);
      org.apache.axis2.transport.TransportUtils.detachInputStream(_returnMessageContext);

      return (com.example.myservice.ws.access.CreateResponseDocument) object;

    } catch (org.apache.axis2.AxisFault f) {

      org.apache.axiom.om.OMElement faultElt = f.getDetail();
      if (faultElt != null) {
        if (faultExceptionNameMap.containsKey(
            new org.apache.axis2.client.FaultMapKey(faultElt.getQName(), "create"))) {
          // make the fault by reflection
          try {
            java.lang.String exceptionClassName =
                faultExceptionClassNameMap.get(
                    new org.apache.axis2.client.FaultMapKey(faultElt.getQName(), "create"));
            java.lang.Class exceptionClass = java.lang.Class.forName(exceptionClassName);
            java.lang.reflect.Constructor constructor =
                exceptionClass.getConstructor(java.lang.String.class);
            java.lang.Exception ex = (java.lang.Exception) constructor.newInstance(f.getMessage());
            // message class
            java.lang.String messageClassName =
                faultMessageMap.get(
                    new org.apache.axis2.client.FaultMapKey(faultElt.getQName(), "create"));
            java.lang.Class messageClass = java.lang.Class.forName(messageClassName);
            java.lang.Object messageObject = fromOM(faultElt, messageClass);
            java.lang.reflect.Method m =
                exceptionClass.getMethod("setFaultMessage", new java.lang.Class[] {messageClass});
            m.invoke(ex, new java.lang.Object[] {messageObject});

            throw new java.rmi.RemoteException(ex.getMessage(), ex);
          } catch (java.lang.ClassCastException e) {
            // we cannot intantiate the class - throw the original Axis fault
            throw f;
          } catch (java.lang.ClassNotFoundException e) {
            // we cannot intantiate the class - throw the original Axis fault
            throw f;
          } catch (java.lang.NoSuchMethodException e) {
            // we cannot intantiate the class - throw the original Axis fault
            throw f;
          } catch (java.lang.reflect.InvocationTargetException e) {
            // we cannot intantiate the class - throw the original Axis fault
            throw f;
          } catch (java.lang.IllegalAccessException e) {
            // we cannot intantiate the class - throw the original Axis fault
            throw f;
          } catch (java.lang.InstantiationException e) {
            // we cannot intantiate the class - throw the original Axis fault
            throw f;
          }
        } else {
          throw f;
        }
      } else {
        throw f;
      }
    } finally {
      if (_messageContext.getTransportOut() != null) {
        _messageContext.getTransportOut().getSender().cleanup(_messageContext);
      }
    }
  }