code: public SegmentStats getStats(ApplicationDefinition appDef, String shard) {
          checkServiceState();
          return m_olap.getStats(appDef, shard);
      }
docs: Get statistics for the given shard, owned by the given application. Statistics are
  returned as a {@link SegmentStats} object. If there is no information for the given
  shard, an IllegalArgumentException is thrown.
  
  @param appDef        OLAP application definition.
  @param shard         Shard name.
  @return              Shard statistics as a {@link SegmentStats} object.