@Override
        public <T> CompletableFuture<List<T>> batchAll(List<? extends Row> actions) {
          List<T> list = new ArrayList<>(actions.size());
          for (Row action : actions) {
            // Row is the index of the loop above where we make WALEntry and Cells.
            int row = Bytes.toInt(action.getRow());
            assertTrue("" + row, row > BOUNDARY);
            UNFILTERED.incrementAndGet();
            list.add(null);
          }
          return CompletableFuture.completedFuture(list);
        }
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