Updated MR based on review comments

ee/app/finders/billed_users_finder.rb

@@ -8,7 +8,7 @@ class BilledUsersFinder
   end
 
   def execute
-    return [] unless group_billed_user_ids.any?
+    return User.none unless group_billed_user_ids.any?
 
     users = ::User.id_in(group_billed_user_ids)
     users = users.search(search_term) if search_term

ee/spec/finders/billed_users_finder_spec.rb

@@ -33,6 +33,14 @@ RSpec.describe BilledUsersFinder do
           expect(subject.execute).to eq([john_smith, john_doe].map(&:user))
         end
       end
+
+      context 'when a sorting parameter is not provided' do
+        subject { described_class.new(group, search_term: search_term) }
+
+        it 'sorts expected results in name_asc order' do
+          expect(subject.execute).to eq([john_doe, john_smith].map(&:user))
+        end
+      end
     end
 
     context 'when a search parameter is not present' do