title: JPA JPQL: select items when attribute of item (list/set) contains another item
body: <pre><code>public class Document extends Model {
  ... 
  @ManyToMany
  public Set&lt;User&gt; accessors;
  ...
  }
  </code></pre>
  
  <p>I want to select all Documents which accessors contain a certain user.
  I have just minimal experiences with SQL and no experiences with JPQL.
  So how to do that?</p>
  
  <p>thanks in advance</p>