Exception from client or from server

Hello Guys!

We got two system, A and B. System A calls B with a webservice-request.
And sometimes we get a WebServiceException/NullpointerException.

I hope you could help me understand from where this exception is arised.

javax.xml.ws.WebServiceException: java.lang.NullPointerException
                            at org.jboss.ws.core.jaxws.JAXBDeserializer.handleUnmarshallException(JAXBDeserializer.java:110)
                            at org.jboss.ws.core.jaxws.JAXBDeserializer.deserialize(JAXBDeserializer.java:78)
                            at org.jboss.ws.core.binding.DeserializerSupport.deserialize(DeserializerSupport.java:58)
                            at org.jboss.ws.core.soap.XMLContent.unmarshallObjectContents(XMLContent.java:179)
                            at org.jboss.ws.core.soap.XMLContent.transitionTo(XMLContent.java:96)
                            at org.jboss.ws.core.soap.SOAPContentElement.transitionTo(SOAPContentElement.java:140)
                            at org.jboss.ws.core.soap.SOAPBodyElementDoc.transitionTo(SOAPBodyElementDoc.java:85)
                            at org.jboss.ws.core.soap.SOAPContentElement.getObjectValue(SOAPContentElement.java:172)
                            at org.jboss.ws.core.EndpointInvocation.transformPayloadValue(EndpointInvocation.java:261)
                            at org.jboss.ws.core.EndpointInvocation.getReturnValue(EndpointInvocation.java:195)
                            at org.jboss.ws.core.CommonClient.syncOutputParams(CommonClient.java:503)
                            at org.jboss.ws.core.CommonClient.invoke(CommonClient.java:389)
                            at org.jboss.ws.core.jaxws.client.ClientImpl.invoke(ClientImpl.java:231)
                            at org.jboss.ws.core.jaxws.client.ClientProxy.invoke(ClientProxy.java:162)
                            at org.jboss.ws.core.jaxws.client.ClientProxy.invoke(ClientProxy.java:148)
                            at $Proxy739.getV7Info(Unknown Source)
                            at se.company.system.a.SystemSI.getTheInfo(SystemSI.java:119)

...but from where did it get thrown?
My guess is that when the response get received at system A there is some deserializing taken place inside jboss and all this happens at the client-side. Because there is something wrong with the response, perhaps system B does no validation,

Or could it be thrown from the server, since it says "$Proxy":
...
at $Proxy739.getV7Info(Unknown Source)


Best regards
Fredrik