Program: 63074
Project: 63074
Buggy source:
@Override protected void encode(ChannelHandlerContext ctx,WeixinResponse response,List<Object> out) throws WeixinException {
  MessageTransfer messageTransfer=ctx.channel().attr(Consts.MESSAGE_TRANSFER_KEY).get();
  AesToken aesToken=messageTransfer.getAesToken();
  EncryptType encryptType=messageTransfer.getEncryptType();
  String weixinId=aesToken.getWeixinId();
  if (StringUtil.isBlank(weixinId)) {
    weixinId=messageTransfer.getToUserName();
  }
  StringBuilder content=new StringBuilder();
  if (response instanceof BlankResponse) {
    content.append(response.toContent());
  }
 else {
    content.append("String_Node_Str");
    content.append(String.format("String_Node_Str",messageTransfer.getFromUserName()));
    content.append(String.format("String_Node_Str",weixinId));
    content.append(String.format("String_Node_Str",System.currentTimeMillis() / 1000l));
    content.append(String.format("String_Node_Str",response.getMsgType()));
    content.append(response.toContent());
    content.append("String_Node_Str");
    if (encryptType == EncryptType.AES) {
      String nonce=RandomUtil.generateString(32);
      String timestamp=String.valueOf(System.currentTimeMillis() / 1000l);
      String encrtypt=MessageUtil.aesEncrypt(weixinId,aesToken.getAesKey(),content.toString());
      String msgSignature=MessageUtil.signature(aesToken.getToken(),nonce,timestamp,encrtypt);
      content.delete(0,content.length());
      content.append("String_Node_Str");
      content.append(String.format("String_Node_Str",nonce));
      content.append(String.format("String_Node_Str",timestamp));
      content.append(String.format("String_Node_Str",msgSignature));
      content.append(String.format("String_Node_Str",encrtypt));
      content.append("String_Node_Str");
    }
  }
  ctx.writeAndFlush(HttpUtil.createHttpResponse(content.toString(),OK,Consts.CONTENTTYPE$APPLICATION_XML));
  logger.info("String_Node_Str",encryptType,content);
}

Fixed version (ground truth):
@Override protected void encode(ChannelHandlerContext ctx,WeixinResponse response,List<Object> out) throws WeixinException {
  MessageTransfer messageTransfer=ctx.channel().attr(Consts.MESSAGE_TRANSFER_KEY).get();
  AesToken aesToken=messageTransfer.getAesToken();
  EncryptType encryptType=messageTransfer.getEncryptType();
  StringBuilder content=new StringBuilder();
  if (response instanceof BlankResponse) {
    content.append(response.toContent());
  }
 else {
    content.append("String_Node_Str");
    content.append(String.format("String_Node_Str",messageTransfer.getFromUserName()));
    content.append(String.format("String_Node_Str",StringUtil.isBlank(aesToken.getWeixinId()) ? messageTransfer.getToUserName() : aesToken.getWeixinId()));
    content.append(String.format("String_Node_Str",System.currentTimeMillis() / 1000l));
    content.append(String.format("String_Node_Str",response.getMsgType()));
    content.append(response.toContent());
    content.append("String_Node_Str");
    if (encryptType == EncryptType.AES) {
      String nonce=RandomUtil.generateString(32);
      String timestamp=String.valueOf(System.currentTimeMillis() / 1000l);
      String encrtypt=MessageUtil.aesEncrypt(aesToken.getWeixinId(),aesToken.getAesKey(),content.toString());
      String msgSignature=MessageUtil.signature(aesToken.getToken(),nonce,timestamp,encrtypt);
      content.delete(0,content.length());
      content.append("String_Node_Str");
      content.append(String.format("String_Node_Str",nonce));
      content.append(String.format("String_Node_Str",timestamp));
      content.append(String.format("String_Node_Str",msgSignature));
      content.append(String.format("String_Node_Str",encrtypt));
      content.append("String_Node_Str");
    }
  }
  ctx.writeAndFlush(HttpUtil.createHttpResponse(content.toString(),OK,Consts.CONTENTTYPE$APPLICATION_XML));
  logger.info("String_Node_Str",encryptType,content);
}