instance method save_belongs_to_association

# File activerecord/lib/active_record/autosave_association.rb, line 533
      def save_belongs_to_association(reflection)
        association = association_instance_get(reflection.name)
        return unless association && association.loaded? && !association.stale_target?

        record = association.load_target
        if record && !record.destroyed?
          autosave = reflection.options[:autosave]

          if autosave && record.marked_for_destruction?
            association.association_route(record).clear_reference(self, fixed_values: false)
            record.destroy
          elsif autosave != false
            saved = if record.new_record? || (autosave && record.changed_for_autosave?)
              begin
                @autosaving_belongs_to_for ||= {}
                @autosaving_belongs_to_for[association] = true
                record.save(validate: !autosave)
              ensure
                @autosaving_belongs_to_for[association] = false
              end
            end

            if association.updated?
              association.association_route(record).write(self, record, force: false)
              association.loaded!
            end

            saved if autosave
          end
        end
      end