code: public static boolean isValidQuery(final RollupQuery rollup_query) {
      return (rollup_query != null && rollup_query.rollup_interval != null &&
        !rollup_query.rollup_interval.isDefaultInterval());
    }
docs: Does it contain a valid rollup interval, mainly says it is not the default
  rollup. Default rollup is of same resolution as raw data. So if true,
  which means the raw cell column qualifier is encoded with the aggregate
  function and the cell is not appended or compacted
  @param rollup_query related RollupQuery object, null if rollup is disabled
  @return true if it is rollup query