def reload
      old_id = @id
      @id = nil

      if @data_dir
        # Read the id file from the data directory if it exists as the
        # ID for the pre-existing physical representation of this machine.
        id_file = @data_dir.join("id")
        id_content = id_file.read.strip if id_file.file?
        if !id_content.to_s.empty?
          @id = id_content
        end
      end

      if @id != old_id && @provider
        # It changed, notify the provider
        @provider.machine_id_changed
      end

      @id
    end
def reload
      old_id = @id
      @id = nil

      if @data_dir
        # Read the id file from the data directory if it exists as the
        # ID for the pre-existing physical representation of this machine.
        id_file = @data_dir.join("id")
        id_content = id_file.read.strip if id_file.file?
        if !id_content.to_s.empty?
          @id = id_content
        end
      end

      if @id != old_id && @provider
        # It changed, notify the provider
        @provider.machine_id_changed
      end

      @id
    end
This reloads the ID of the underlying machine.