code: public void finishJson(final JsonConvert convert, final org.redkale.service.RetResult ret) {
          this.contentType = this.jsonContentType;
          if (this.recycleListener != null) this.output = ret;
          if (ret != null && !ret.isSuccess()) {
              this.header.addValue("retcode", String.valueOf(ret.getRetcode()));
              this.header.addValue("retinfo", ret.getRetinfo());
          }
          finish(convert.convertTo(getBodyBufferSupplier(), ret));
      }
docs: 将RetResult对象以JSON格式输出
  
  @param convert 指定的JsonConvert
  @param ret     RetResult输出对象