Add issue sidebar and toggle_subscription endpoint in board issues data

app/controllers/boards/issues_controller.rb

@@ -84,6 +84,7 @@ module Boards
       resource.as_json(
         only: [:id, :iid, :project_id, :title, :confidential, :due_date, :relative_position],
         labels: true,
+        sidebar_endpoints: true,
         include: {
           project: { only: [:id, :path] },
           assignees: { only: [:id, :name, :username], methods: [:avatar_url] },

app/models/issue.rb

@@ -246,7 +246,12 @@ class Issue < ActiveRecord::Base
 
   def as_json(options = {})
     super(options).tap do |json|
-      json[:subscribed] = subscribed?(options[:user], project) if options.key?(:user) && options[:user]
+      if options.key?(:sidebar_endpoints) && project
+        url_helper = Gitlab::Routing.url_helpers
+
+        json.merge!(issue_sidebar_endpoint: url_helper.project_issue_path(project, self, format: :json, serializer: 'sidebar'),
+                    toggle_subscription_endpoint: url_helper.toggle_subscription_project_issue_path(project, self))
+      end
 
       if options.key?(:labels)
         json[:labels] = labels.as_json(

spec/fixtures/api/schemas/issue.json

@@ -13,6 +13,8 @@
     "confidential": { "type": "boolean" },
     "due_date": { "type": ["date", "null"] },
     "relative_position": { "type": "integer" },
+    "issue_sidebar_endpoint": { "type": "string" },
+    "toggle_subscription_endpoint": { "type": "string" },
     "project": {
       "id": { "type": "integer" },
       "path": { "type": "string" }