Soap document Validation on webmethods

Today, I am experiencing the problem of dealing with webmethods on consuming service generated by processing wsdl of JIRA's application. Well, I definitely experience an error message on dealing with this. Here it is:

com.wm.app.b2b.server.ServiceException: [ISS.0088.9139] Output parameters do not conform to targetOutputSignature:
errorCode=VV-004

The above is caused by validation that is done by webmethods after receiving the object during the soap service calling. All the fields on the object will be validated and if the fields' value does not match (even, the value is empty or null). It will complain. It is very annoying if you receive an object which does not have any value or we can say it as null. it keeps poping up an error message as mentioned above.

However, I found weakness of this validation. It seems that webmethods is not trying to match between the object's fields and the document as reference for validation. Thus, if the fields in the object being retrieved does not exist in the document, then there will be no validation being done.