code: private void addMimeHeaders(SoapMessage response, Message replyMessage) {
          for (Entry<String, Object> headerEntry : replyMessage.getHeaders().entrySet()) {
              if (headerEntry.getKey().toLowerCase().startsWith(SoapMessageHeaders.HTTP_PREFIX)) {
                  String headerName = headerEntry.getKey().substring(SoapMessageHeaders.HTTP_PREFIX.length());
                  
                  if (response instanceof SaajSoapMessage) {
                      SaajSoapMessage saajSoapMessage = (SaajSoapMessage) response;
                      MimeHeaders headers = saajSoapMessage.getSaajMessage().getMimeHeaders();
                      headers.setHeader(headerName, headerEntry.getValue().toString());
                  } else if (response instanceof AxiomSoapMessage) {
                      log.warn("Unable to set mime message header '" + headerName + "' on AxiomSoapMessage - unsupported");
                  } else {
                      log.warn("Unsupported SOAP message implementation - unable to set mime message header '" + headerName + "'");
                  }
              }
          }
      }
docs: Adds mime headers outside of SOAP envelope. Header entries that go to this header section
  must have internal http header prefix defined in {@link com.consol.citrus.ws.message.SoapMessageHeaders}.
  @param response the soap response message.
  @param replyMessage the internal reply message.