code: public static void setPinned(FileSystem fs, AlluxioURI path, boolean pinned)
        throws AlluxioException, IOException {
      SetAttributePOptions options = SetAttributePOptions.newBuilder().setPinned(pinned).build();
      fs.setAttribute(path, options);
    }
docs: Sets pin state for the input path.
  
  @param fs The {@link FileSystem} client
  @param path The {@link AlluxioURI} path as the input of the command
  @param pinned the state to be set