protected void addRequestHeaders(Hashtable headers) {
   if (connection == null || headers == null) return;
   Enumeration keys = headers.keys();
   while (keys.hasMoreElements()) {
     String keyValue = (String) keys.nextElement();
     String headerValue = (String) headers.get(keyValue);
     addRequestHeaders(keyValue, headerValue);
   }
 }
 private byte[] sendHttpMessage(byte[] body) throws IOException {
   HttpMessageContext context = HttpMessageContext.getInstance();
   context.Debug("GNHttpConnection [sendHttpMessage] starts");
   if (context.getLogheader()) {
     context.Info(logMessageSetting());
   }
   connection.setDoInput(true);
   if (body != null) {
     connection.setDoOutput(true);
     OutputStream os = TimedURLConnection.getOutputStream(connection, timeout * 1000);
     context.Debug("GNHttpConnection [sendHttpMessage] sending message ...");
     os.write(body);
     context.Debug("GNHttpConnection [sendHttpMessage] message sent");
   }
   context.Debug(
       "GNHttpConnection [sendHttpMessage] TimedURLConnection.getInputStream timeout["
           + timeout
           + " S]");
   InputStream is = TimedURLConnection.getInputStream(connection, timeout * 1000);
   responseCode = connection.getResponseCode();
   context.Debug("GNHttpConnection [sendHttpMessage] responseCode[" + responseCode + "]");
   responseMessage = HttpMessageContext.getMessage(is);
   responseheaders = new Hashtable<String, String>();
   int no = 0;
   while (true) {
     String headerName = connection.getHeaderFieldKey(no);
     String headerValue = connection.getHeaderField(no);
     if (headerName != null && headerName.length() > 0) {
       responseheaders.put(headerName, headerValue);
     } else {
       if (headerValue == null || headerValue.length() <= 0) break;
     }
     no++;
   }
   if (context.getLogheader()) {
     GTConfigFile head = new GTConfigFile(responseheaders);
     context.Debug("GNHttpConnection [sendHttpMessage] responseHeader\r\n" + head);
     context.Debug(
         "GNHttpConnection [sendHttpMessage] responseMessage\r\n"
             + new String(getResponseMessage()));
     context.Info("GNHttpConnection [sendHttpMessage] success for " + url);
   } else context.Info("GNHttpConnection [sendHttpMessage] success for " + url);
   return responseMessage;
 }