title: Embedded entities in Objectify don't appear to auto-generate an Id
body: <p>I'm using Objectify with my first serious Google App Engine project, and generally it's all going swimmingly (what a lovely library!). Unfortunately, I've come across a problem when persisting my entities.</p>
  
  <p>My basic structure is as follows:</p>
  
  <pre><code>@Entity
  class Parent {
      @Id
      long id = 123;
      @Embedded
      Child[] children;
  }
  
  @Entity
  class Child {
      @Id
      Long id;
  }
  </code></pre>
  
  <p>I am manually declaring the ids of the parent entities, but I want the embedded child entities to automatically generate an id. I did wonder about just removing the @Id in the child entity entirely and coding around it, but then I get errors about entities needing the @Id.</p>
  
  <p>Can someone please help? I am using the id, in order to compare changes between parent entities' children, so it's fairly fundamental to the current way I've designed it. I can re-architect though, if that would be a better solution.</p>