@Override
    public boolean filter(TableName table, long writeTime) {
      boolean b = writeTime <= BOUNDARY;
      if (b) {
        FILTERED.incrementAndGet();
      }
      return b;
    }
Simple filter that will filter out any entry wholse writeTime is <= 5.
hbase-server/src/test/java/org/apache/hadoop/hbase/replication/regionserver/TestWALEntrySinkFilter.java