Create 'alias' routes for Epics

ee/lib/api/epic_issues.rb

@@ -55,13 +55,15 @@ module API
       params do
         requires :epic_iid, type: Integer, desc: 'The iid of the epic'
       end
-      get ':id/(-/)epics/:epic_iid/issues' do
+      [':id/epics/:epic_iid/issues', ':id/-/epics/:epic_iid/issues'].each do |path|
+        get path do
           authorize_can_read!
 
           present epic.issues_readable_by(current_user),
             with: EE::API::Entities::EpicIssue,
             current_user: current_user
         end
+      end
 
       desc 'Assign an issue to the epic' do
         success EE::API::Entities::EpicIssueLink

ee/lib/api/epics.rb

@@ -39,13 +39,15 @@ module API
         optional :my_reaction_emoji, type: String, desc: 'Return epics reacted by the authenticated user by the given emoji'
         use :pagination
       end
-      get ':id/(-/)epics' do
+      [':id/epics', ':id/-/epics'].each do |path|
+        get path do
           epics = paginate(find_epics(finder_params: { group_id: user_group.id })).with_api_entity_associations
 
           # issuable_metadata has to be set because `Entities::Epic` doesn't inherit from `Entities::IssuableEntity`
           extra_options = { issuable_metadata: Gitlab::IssuableMetadata.new(current_user, epics).data, with_labels_details: declared_params[:with_labels_details] }
           present epics, epic_options.merge(extra_options)
         end
+      end
 
       desc 'Get details of an epic' do
         success EE::API::Entities::Epic