title: appengine sees User as additional parameter
body: <p>I am using OAuth with my app-engine server. It's rather simple to do, simple add <code>User</code> as one of the parameters. But when I do I get the compile error</p>
  
  <blockquote>
    <p>Multiple entity parameters. there can only be a single entity
    parameter per method...</p>
  </blockquote>
  
  <pre><code>@ApiMethod(path = "updateDocument", name = "updateDocument", httpMethod = ApiMethod.HttpMethod.POST)
  public void updateDocument(User user, MyDocument input){
    ...
  }
  </code></pre>
  
  <hr>
  
  <p>It works fine for the methods of the form</p>
  
  <pre><code>public MyBean sayHiUser(@Named("name") String name, User user)
  </code></pre>
  
  <p>It just doesn't work when I have custom objects like <code>MyDocument</code>.</p>