static Class<? extends StoreFileTrackerBase>
    getStoreFileTrackerClassForMigration(Configuration conf, String configName) {
    String trackerName =
      Preconditions.checkNotNull(conf.get(configName), "config %s is not set", configName);
    try {
      return Trackers.valueOf(trackerName.toUpperCase()).clazz
        .asSubclass(StoreFileTrackerBase.class);
    } catch (IllegalArgumentException e) {
      // Fall back to them specifying a class name
      try {
        return Class.forName(trackerName).asSubclass(StoreFileTrackerBase.class);
      } catch (ClassNotFoundException cnfe) {
        throw new RuntimeException(cnfe);
      }
    }
  }
Used at master side when splitting/merging regions, as we do not have a Store, thus no
StoreContext at master side.
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/storefiletracker/StoreFileTrackerFactory.java