Add an option to user make an issue confidential

app/controllers/projects/issues_controller.rb

@@ -158,7 +158,7 @@ class Projects::IssuesController < Projects::ApplicationController
 
   def issue_params
     params.require(:issue).permit(
-      :title, :assignee_id, :position, :description,
+      :title, :assignee_id, :position, :description, :confidential,
       :milestone_id, :state_event, :task_num, label_ids: []
     )
   end

app/views/shared/issuable/_form.html.haml

@@ -29,6 +29,15 @@
       = render 'projects/notes/hints'
       .clearfix
       .error-alert
+
+- if issuable.is_a?(Issue) && !issuable.project.private?
+  .form-group
+    .col-sm-offset-2.col-sm-10
+      .checkbox
+        = f.label :confidential do
+          = f.check_box :confidential
+          This issue is confidential and should only be visible to team members
+
 - if can?(current_user, :"admin_#{issuable.to_ability_name}", issuable.project)
   %hr
   .form-group