public static Class<? extends StoreFileTracker> getTrackerClass(String trackerNameOrClass) {
    try {
      Trackers tracker = Trackers.valueOf(trackerNameOrClass.toUpperCase());
      return tracker.clazz;
    } catch (IllegalArgumentException e) {
      // Fall back to them specifying a class name
      try {
        return Class.forName(trackerNameOrClass).asSubclass(StoreFileTracker.class);
      } catch (ClassNotFoundException e1) {
        throw new RuntimeException(e1);
      }
    }
  }
Maps between configuration names for trackers and implementation classes.
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/storefiletracker/StoreFileTrackerFactory.java