docs: public ByteBuf preprocessJson(Integer jsonIndex, ByteBuf content) throws IOException {
          String packet = URLDecoder.decode(content.toString(CharsetUtil.UTF_8), CharsetUtil.UTF_8.name());
  
          if (jsonIndex != null) {
              /**
              * double escaping is required for escaped new lines because unescaping of new lines can be done safely on server-side
              * (c) socket.io.js
              *
              * @see https://github.com/Automattic/socket.io-client/blob/1.3.3/socket.io.js#L2682
              */
              packet = packet.replace("\\\\n", "\\n");
  
              // skip "d="
              packet = packet.substring(2);
          }
  
          return Unpooled.wrappedBuffer(packet.getBytes(CharsetUtil.UTF_8));
      }