code: @Override
    public UfsClient get(long mountId) throws NotFoundException, UnavailableException {
      try {
        return super.get(mountId);
      } catch (NotFoundException e) {
        // Not cached locally, let's query master
      }
  
      UfsInfo info;
      try {
        info = mMasterClient.getUfsInfo(mountId);
      } catch (IOException e) {
        throw new UnavailableException(
            String.format("Failed to create UFS info for mount point with id %d", mountId), e);
      }
      Preconditions.checkState((info.hasUri() && info.hasProperties()), "unknown mountId");
      super.addMount(mountId, new AlluxioURI(info.getUri()),
          UnderFileSystemConfiguration.defaults(ServerConfiguration.global())
              .setReadOnly(info.getProperties().getReadOnly())
              .setShared(info.getProperties().getShared())
              .createMountSpecificConf(info.getProperties().getPropertiesMap()));
      UfsClient ufsClient = super.get(mountId);
      return ufsClient;
    }
docs: {@inheritDoc}.
  
  If this mount id is new to this worker, this method will query master to get the
  corresponding ufs info.