CE port for bulk updating group labels

- Original EE MR: https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/14827

app/models/issue.rb

@@ -43,6 +43,7 @@ class Issue < ApplicationRecord
   validates :project, presence: true
 
   alias_attribute :parent_ids, :project_id
+  alias_method :issuing_parent, :project
 
   scope :in_projects, ->(project_ids) { where(project_id: project_ids) }
 

app/models/merge_request.rb

@@ -192,6 +192,7 @@ class MergeRequest < ApplicationRecord
   alias_attribute :project, :target_project
   alias_attribute :project_id, :target_project_id
   alias_attribute :auto_merge_enabled, :merge_when_pipeline_succeeds
+  alias_method :issuing_parent, :target_project
 
   def self.reference_prefix
     '!'

app/services/issuable/bulk_update_service.rb

@@ -29,7 +29,7 @@ module Issuable
       items.each do |issuable|
         next unless can?(current_user, :"update_#{type}", issuable)
 
-        update_class.new(issuable.project, current_user, params).execute(issuable)
+        update_class.new(issuable.issuing_parent, current_user, params).execute(issuable)
       end
 
       {

app/views/groups/issues.html.haml

-- @can_bulk_update = can?(current_user, :admin_issue, @group)
+- @can_bulk_update = can?(current_user, :admin_issue, @group) && @group.feature_available?(:group_bulk_edit)
 
 - page_title "Issues"
 = content_for :meta_tags do

app/views/groups/merge_requests.html.haml

-- @can_bulk_update = can?(current_user, :admin_merge_request, @group)
+- @can_bulk_update = can?(current_user, :admin_merge_request, @group) && @group.feature_available?(:group_bulk_edit)
 
 - page_title "Merge Requests"
 

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

 - project = @target_project || @project
+- edit_context = local_assigns.fetch(:edit_context, nil) || project
 - show_create = local_assigns.fetch(:show_create, true)
 - extra_options = local_assigns.fetch(:extra_options, true)
 - filter_submit = local_assigns.fetch(:filter_submit, true)
@@ -8,7 +9,7 @@
 - classes = local_assigns.fetch(:classes, [])
 - selected = local_assigns.fetch(:selected, nil)
 - dropdown_title = local_assigns.fetch(:dropdown_title, "Filter by label")
-- dropdown_data = label_dropdown_data(@project, labels: labels_filter_path_with_defaults, default_label: "Labels")
+- dropdown_data = label_dropdown_data(edit_context, labels: labels_filter_path_with_defaults(only_group_labels: edit_context.is_a?(Group)), default_label: "Labels")
 - dropdown_data.merge!(data_options)
 - label_name = local_assigns.fetch(:label_name, "Labels")
 - no_default_styles = local_assigns.fetch(:no_default_styles, false)

doc/user/group/bulk_editing/index.md

-# Bulk editing issue and merge request milestones **(PREMIUM)**
+# Bulk editing issues, merge requests, and epics at the group level **(PREMIUM)**
 
-> - [Introduced](https://gitlab.com/gitlab-org/gitlab-ee/issues/7249) for issues in
-  [GitLab Premium](https://about.gitlab.com/pricing/) 12.1.
-> - [Introduced](https://gitlab.com/gitlab-org/gitlab-ee/issues/12719) for merge
-  requests in GitLab [GitLab Premium](https://about.gitlab.com/pricing/) 12.2.
+> - [Introduced](https://gitlab.com/gitlab-org/gitlab-ee/issues/7249) for issues in [GitLab Premium](https://about.gitlab.com/pricing/) 12.1.
+> - [Introduced](https://gitlab.com/gitlab-org/gitlab-ee/issues/12719) for merge requests in [GitLab Premium](https://about.gitlab.com/pricing/) 12.2.
+> - [Introduced](https://gitlab.com/gitlab-org/gitlab-ee/issues/7250) for epics in [GitLab Premium](https://about.gitlab.com/pricing/) 12.2.
 
-Milestones can be updated simultaneously across multiple issues or merge requests by using the bulk editing feature.
+## Editing milestones and labels
 
-![Bulk editing](img/bulk-editing.png)
+> **Notes:**
+>
+> - A permission level of `Reporter` or higher is required in order to manage issues.
+> - A permission level of `Developer` or higher is required in order to manage merge requests.
+> - A permission level of `Reporter` or higher is required in order to manage epics.
+
+By using the bulk editing feature:
 
-NOTE: **Note:**
-A permission level of `Reporter` or higher is required in order to manage issues, and
-a permission level of `Developer` or higher is required in order to manage merge requests.
+- Milestones can be updated simultaneously across multiple issues or merge requests.
+- Labels can be updated simultaneously across multiple issues, merge requests, or epics.
+
+![Bulk editing](img/bulk-editing.png)
 
-To bulk update group issue or merge request milestones:
+To bulk update group issues, merge requests, or epics:
 
-1. Navigate to the issues or merge requests list.
-1. Click the **Edit issues** or **Edit merge requests** button.
-   - This will open a sidebar on the right-hand side of your screen where an editable field
-     for milestones will be displayed.
-   - Checkboxes will also appear beside each issue or merge request.
-1. Check the checkbox beside each issue to be edited.
-1. Select the desired milestone from the sidebar.
+1. Navigate to the issues, merge requests, or epics list.
+1. Click **Edit issues**, **Edit merge requests**, or **Edit epics**.
+    - This will open a sidebar on the right-hand side where editable fields
+      for milestones and labels will be displayed.
+    - Checkboxes will also appear beside each issue, merge request, or epic.
+1. Check the checkbox beside each issue, merge request, or epic to be edited.
+1. Select the desired new values from the sidebar.
 1. Click **Update all**.

doc/user/group/epics/index.md

@@ -97,6 +97,22 @@ have a [start or due date](#start-date-and-due-date), then you can see a
 
 Drag and drop to reorder issues and child epics. New issues and child epics added to an epic appear at the top of the list.
 
+## Updating epics
+
+### Using bulk editing
+
+To apply labels across multiple epics:
+
+1. Go to the Epics list.
+1. Click **Edit epics**.
+    - Checkboxes will appear beside each epic.
+    - A sidebar on the right-hand side will appear, with an editable field for labels.
+1. Check the checkbox beside each epic to be edited.
+1. Select the desired labels.
+1. Click **Update all**.
+
+![bulk editing](img/bulk_editing.png)
+
 ## Deleting an epic
 
 NOTE: **Note:**