List only labels that belongs to the group on the group issues page

app/controllers/dashboard/labels_controller.rb

 class Dashboard::LabelsController < Dashboard::ApplicationController
   def index
-    labels = LabelsFinder.new(current_user, project_id: projects)
-                         .execute
-                         .select(:id, :title, :color)
-                         .uniq(:title)
-
     respond_to do |format|
-      format.json { render json: labels }
+      format.json { render json: LabelsFinder.new(current_user).execute }
     end
   end
 end

app/controllers/groups/labels_controller.rb

@@ -8,9 +8,17 @@ class Groups::LabelsController < Groups::ApplicationController
   respond_to :html
 
   def index
+    respond_to do |format|
+      format.html do
         @labels = @group.labels.page(params[:page])
       end
 
+      format.json do
+        render json: LabelsFinder.new(current_user, group_id: @group.id).execute
+      end
+    end
+  end
+
   def new
     @label = @group.labels.new
   end

app/finders/labels_finder.rb

@@ -20,13 +20,17 @@ class LabelsFinder < UnionFinder
     label_ids << Label.where(project_id: projects.select(:id)).select(:id)
   end
 
+  def sort(items)
+    items.reorder(title: :asc, type: :desc)
+  end
+
   def with_title(items)
     items = items.where(title: title) if title.present?
     items
   end
 
-  def sort(items)
-    items.reorder(title: :asc)
+  def group_id
+    params[:group_id].presence
   end
 
   def project_id
@@ -40,13 +44,10 @@ class LabelsFinder < UnionFinder
   def projects
     return @projects if defined?(@projects)
 
-    if project_id
     @projects = ProjectsFinder.new.execute(current_user)
-                                    .where(id: project_id)
-                                    .reorder(nil)
-    else
-      @projects = Project.none
-    end
+    @projects = @projects.joins(:namespace).where(namespaces: { id: group_id, type: 'Group' }) if group_id
+    @projects = @projects.where(id: project_id) if project_id
+    @projects = @projects.reorder(nil)
 
     @projects
   end

app/helpers/labels_helper.rb

@@ -172,7 +172,10 @@ module LabelsHelper
   end
 
   def labels_filter_path
+    return group_labels_path(@group, :json) if @group
+
     project = @target_project || @project
+
     if project
       namespace_project_labels_path(project.namespace, project, :json)
     else