docs: public String getMessageCode(BaseMessage externalMessage)
      {
          if (!(externalMessage.getExternalMessage() instanceof SoapTrxMessageIn))
              return null;
          SOAPMessage message = (SOAPMessage)((SoapTrxMessageIn)externalMessage.getExternalMessage()).getRawData();
          try {
              // Message creation takes care of creating the SOAPPart - a
              // required part of the message as per the SOAP 1.1
              // specification.
              SOAPPart sp = message.getSOAPPart();
              
              // Retrieve the envelope from the soap part to start building
              // the soap message.
              SOAPEnvelope envelope = sp.getEnvelope();
              
              // Create a soap header from the envelope.
              //?SOAPHeader hdr = envelope.getHeader();
              
              // Get the body
              SOAPBody body = envelope.getBody();
              SOAPElement element = this.getElement(body, null);
              if (element != null)
                  return element.getElementName().getLocalName();   // The operation            
          } catch(Throwable ex) {
              ex.printStackTrace();
          }
          return null;    // No type found.
      }