Merge branch 'remove-todo-explose-nil' into 'master'

Remove TODO about using expose_nil

See merge request gitlab-org/gitlab!49239

lib/api/entities/project_import_status.rb

@@ -12,9 +12,8 @@ module API
         project.import_state&.relation_hard_failures(limit: 100) || []
       end
 
-      # TODO: Use `expose_nil` once we upgrade the grape-entity gem
-      expose :import_error, if: lambda { |project, _ops| project.import_state&.last_error } do |project|
-        project.import_state.last_error
+      expose :import_error do |project, _options|
+        project.import_state&.last_error
       end
     end
   end