title: Which annotation should I use: @IdClass or @EmbeddedId
body: <p>The <code>JPA</code> (Java Persistence API) specification has 2 different ways to specify entity composite keys: <code>@IdClass</code> and <code>@EmbeddedId</code>. </p>
  
  <p>I'm using both annotations on my mapped entities, but it turns out to be a big mess to people who aren't very familiar with <code>JPA</code>. </p>
  
  <p>I want to adopt only one way to specify composite keys. Which one is really the best? Why?</p>