title: How to use spring Repository without @Id?
body: <p>I'm using spring <code>CrudRepository</code> throughout my application.
  Now I want to also create one for an <code>@Entity</code> that does not have an <code>@Id</code>. Is that possible at all?</p>
  
  <pre><code>//probably ID is always required?
  public interface Repository&lt;T, ID extends Serializable&gt;
  </code></pre>