@Override
    public void run() {
      super.run();
    }
Install a shutdown hook that calls stop on the passed Stoppable and then thread joins against
the passed <code>threadToJoin</code>. When this thread completes, it then runs the hdfs thread
(This install removes the hdfs shutdown hook keeping a handle on it to run it after
<code>threadToJoin</code> has stopped).
<p>
To suppress all shutdown hook handling -- both the running of the regionserver hook and of the
hdfs hook code -- set {@link ShutdownHook#RUN_SHUTDOWN_HOOK} in {@link Configuration} to
<code>false</code>. This configuration value is checked when the hook code runs.
@param fs           Instance of Filesystem used by the RegionServer
@param stop         Installed shutdown hook will call stop against this passed
                    <code>Stoppable</code> instance.
@param threadToJoin After calling stop on <code>stop</code> will then join this thread.
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/ShutdownHook.java