def on_update
      @model_class.before_save { |r|
        r.paper_trail.reset_timestamp_attrs_for_update_if_needed
      }
      @model_class.after_update { |r|
        if r.paper_trail.save_version?
          r.paper_trail.record_update(
            force: false,
            in_after_callback: true,
            is_touch: false
          )
        end
      }
      @model_class.after_update { |r|
        r.paper_trail.clear_version_instance
      }
      return if @model_class.paper_trail_options[:on].include?(:update)
      @model_class.paper_trail_options[:on] << :update
    end
def on_update
      @model_class.before_save { |r|
        r.paper_trail.reset_timestamp_attrs_for_update_if_needed
      }
      @model_class.after_update { |r|
        if r.paper_trail.save_version?
          r.paper_trail.record_update(
            force: false,
            in_after_callback: true,
            is_touch: false
          )
        end
      }
      @model_class.after_update { |r|
        r.paper_trail.clear_version_instance
      }
      return if @model_class.paper_trail_options[:on].include?(:update)
      @model_class.paper_trail_options[:on] << :update
    end
Adds a callback that records a version after an "update" event.

 @api public