docs: private String parseParamsForStatistics(ParameterSet params, JSONObject obj) throws Exception
      {
          if ((params.toArray().length < 1) || (params.toArray().length > 2)) {
              return "Incorrect number of arguments to @Statistics (expects 2, received " +
                      params.toArray().length + ")";
          }
          Object first = params.toArray()[0];
          if (!(first instanceof String)) {
              return "First argument to @Statistics must be a valid STRING selector, instead was " +
                      first;
          }
          String subselector = (String)first;
          try {
              StatsSelector s = StatsSelector.valueOf(subselector.toUpperCase());
              subselector = s.name();
          }
          catch (Exception e) {
              return "First argument to @Statistics must be a valid STRING selector, instead was " +
                      first;
          }
  
          boolean interval = false;
          if (params.toArray().length == 2) {
              interval = ((Number)(params.toArray()[1])).longValue() == 1L;
          }
          obj.put("subselector", subselector);
          obj.put("interval", interval);
  
          return null;
      }