code: @Override
    public synchronized void initialize(URI uri, org.apache.hadoop.conf.Configuration conf)
        throws IOException {
      initialize(uri, conf, null);
    }
docs: {@inheritDoc}
  
  Sets up a lazy connection to Alluxio through mFileSystem. This must be called before client
  operations.
  
  If it is called twice on the same object concurrently, one of the thread will do the
  initialization work, the other will wait until initialization is done.
  If it is called after initialized, then this is a noop.