I just rewritten the above method declaration like below, it worked out.
public JAXBElement<com.schema.get_response.v2.GetResponseType> handleGetresponse(@RequestPayload JAXBElement<String> Soaprequest){
.......................................
/* how to process the Soaprequest which contains the byte[] of base64Binary objects*/
}
change description: Declaration changed from JAXBElement<Byte> to JAXBElement<String>