@Override
    public ReturnCode filterCell(final Cell v) {
      if (count++ < NUM_COLS) {
        return ReturnCode.INCLUDE;
      }
      return ReturnCode.SKIP;
    }
To test behavior of filters at server from region side.
hbase-server/src/test/java/org/apache/hadoop/hbase/filter/TestFilterFromRegionSide.java