code: public static boolean waitCompleted(FileSystem fs, AlluxioURI uri)
        throws IOException, AlluxioException, InterruptedException {
      return FileSystemUtils.waitCompleted(fs, uri, -1, TimeUnit.MILLISECONDS);
    }
docs: Shortcut for {@code waitCompleted(fs, uri, -1, TimeUnit.MILLISECONDS)}, i.e., wait for an
  indefinite amount of time. Note that if a file is never completed, the thread will block
  forever, so use with care.
  
  @param fs a {@link FileSystem} instance
  @param uri the URI of the file on which the thread should wait
  @return true if the file is complete when this method returns and false if the method timed out
  before the file was complete.
  @throws InterruptedException if the thread receives an interrupt while waiting for file
  completion
  @see #waitCompleted(FileSystem, AlluxioURI, long, TimeUnit)