code: @Override
      protected String format(String request) {
          String result = request;
          if (request != null && !"".equals(request)) {
              try {
                  JsonNode rootNode = mapper.readValue(request, JsonNode.class);
                  result = mapper.writeValueAsString(rootNode);
              } catch (Exception e) {
                  log.error(null, e);
              }
          }
          return result;
      }
docs: {@inheritDoc}