### Expected behavior and actual behavior.

- What did you expect to happen?
- What happened? Include as much information as possible, such as:
  - Nature of reported defect (e.g. user name missing, not "It doesn't work."). Is it intermittent?
  - The best help here is a failing test. Even better if it's a PR.
  - Then the steps to reproduce and/or a gist or repository that demonstrates the defect.
  - Then examples of the code you were using.
  - Any error messages (including stacktrace, i.e. "Show me the error.")

### Steps to reproduce the issue (i.e. "Show me how to show myself." )

- What were you doing? Include code if possible, such as:
  - Command line parameters used, if any.
  - RubyGems code in your Gemfile, if any. Gemfile.lock, if possible.
  - Any configuration you've made.
- Things you've tried.
- Link to source code, if available.

### Specifications

- ActiveModelSerializers version (0.8.x, 0.9.x, 0.10.x, commit ref).
- What are you using ActiveModelSerializers with? Rails? Grape? Other? Which versions?
- If you are not running the latest version (please check), and you cannot update it,
  please specify in your report why you can't update to the latest version.
- Ruby version with patch level.  And whether you're using rvm, rbenv, etc.
  - Include `ruby -e "puts RUBY_DESCRIPTION"`.
- Operating system type + version. e.g. Mac OSX Snow Leopard

For more general guidelines, see [Filing an
issue](https://github.com/rails-api/active_model_serializers/blob/master/CONTRIBUTING.md#filing-an-issue).