Present "plan" data for group/namespace admins

doc/api/namespaces.md

@@ -38,7 +38,8 @@ Example response:
     "kind": "group"
     "full_path": "group1",
     "parent_id": "null",
-    "members_count_with_descendants": 2
+    "members_count_with_descendants": 2,
+    "plan": "bronze"
   },
   {
     "id": 3,
@@ -51,7 +52,7 @@ Example response:
 ]
 ```
 
-**Note**: `members_count_with_descendants` are presented only for group masters/owners.
+**Note**: `members_count_with_descendants` and `plan` are presented only for group masters/owners.
 
 ## Search for namespace
 

lib/api/entities.rb

@@ -522,7 +522,7 @@ module API
 
       # EE-only
       expose :shared_runners_minutes_limit, if: lambda { |_, options| options[:current_user]&.admin? }
-      expose :plan, if: lambda { |_, options| options[:current_user]&.admin? }
+      expose :plan, if: -> (namespace, opts) { Ability.allowed?(opts[:current_user], :admin_namespace, namespace) }
     end
 
     class MemberAccess < Grape::Entity

spec/requests/api/namespaces_spec.rb

@@ -61,7 +61,7 @@ describe API::Namespaces do
         owned_group_response = json_response.find { |resource| resource['id'] == group1.id }
 
         expect(owned_group_response.keys).to contain_exactly('id', 'kind', 'name', 'path', 'full_path',
-                                                             'parent_id', 'members_count_with_descendants')
+                                                             'plan', 'parent_id', 'members_count_with_descendants')
       end
 
       it "returns correct attributes when user cannot admin group" do