@Override
  public void insertNewFiles(Collection<HStoreFile> sfs) {
    CompactionOrFlushMergeCopy cmc = new CompactionOrFlushMergeCopy(true);
    cmc.mergeResults(Collections.emptyList(), sfs);
    debugDumpState("Added new files");
  }
Normally invalid key is null, but in the map null is the result for "no key"; so use the
following constant value in these maps instead. Note that this is a constant and we use it to
compare by reference when we read from the map.
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/StripeStoreFileManager.java