docs: @Override
      protected void populateColumnSchema(ArrayList<ColumnInfo> columns) {
          super.populateColumnSchema(columns);
          columns.add(new ColumnInfo(VoltSystemProcedure.CNAME_SITE_ID, VoltSystemProcedure.CTYPE_ID));
          columns.add(new ColumnInfo(Columns.PARTITION_ID, VoltType.BIGINT));
          columns.add(new ColumnInfo(Columns.SOURCE_NAME, VoltType.STRING));
          columns.add(new ColumnInfo(Columns.EXPORT_TARGET, VoltType.STRING));
          columns.add(new ColumnInfo(Columns.ACTIVE, VoltType.STRING));
          columns.add(new ColumnInfo(Columns.TUPLE_COUNT, VoltType.BIGINT));
          columns.add(new ColumnInfo(Columns.TUPLE_PENDING, VoltType.BIGINT));
          columns.add(new ColumnInfo(Columns.LAST_QUEUED_TIMESTAMP, VoltType.TIMESTAMP));
          columns.add(new ColumnInfo(Columns.LAST_ACKED_TIMESTAMP, VoltType.TIMESTAMP));
          columns.add(new ColumnInfo(Columns.AVERAGE_LATENCY, VoltType.BIGINT));
          columns.add(new ColumnInfo(Columns.MAX_LATENCY, VoltType.BIGINT));
          columns.add(new ColumnInfo(Columns.QUEUE_GAP, VoltType.BIGINT));
          columns.add(new ColumnInfo(Columns.STATUS, VoltType.STRING));
      }