Prevent disclosure of done ratio in API v3

lib/api/v3/work_packages/work_package_representer.rb

@@ -216,7 +216,7 @@ module API
         property :start_date, getter: -> (*) { model.start_date.to_datetime.utc.iso8601 unless model.start_date.nil? }, render_nil: true
         property :due_date, getter: -> (*) { model.due_date.to_datetime.utc.iso8601 unless model.due_date.nil? }, render_nil: true
         property :estimated_time, render_nil: true
-        property :percentage_done, render_nil: true
+        property :percentage_done, render_nil: true, exec_context: :decorator
         property :version_id, getter: -> (*) { model.fixed_version.try(:id) }, render_nil: true
         property :version_name,  getter: -> (*) { model.fixed_version.try(:name) }, render_nil: true
         property :project_id, getter: -> (*) { model.project.id }
@@ -265,6 +265,10 @@ module API
         def visible_children
           @visible_children ||= represented.model.children.find_all { |child| child.visible? }
         end
+
+        def percentage_done
+          (Setting.work_package_done_ratio == 'disabled') ? nil : represented.percentage_done
+        end
       end
     end
   end