title: Saving bidirectional ManyToMany
body: <p>I have two entity classes annotated in the following way</p>
  
  <pre><code>@Entity
  class A {
     @ManyToMany(mappedBy="A", cascade=CascadeType.ALL)
     private List&lt;B&gt; b;
   ..
  }
  
  @Entity
  class B {
     @ManyToMany(cascade=CascadeType.ALL)
     private List&lt;A&gt; a;
   ..
  }
  </code></pre>
  
  <p>If I store an instance of the class 'B', the relations are stored in the database and the getter in class 'A' will return the correct subset of B's. However, if I make changes to the list of Bs in 'A', the changes are not stored in the database?</p>
  
  <p>My question is, how can I make it so that changes in either class are "cascaded" to the other class?</p>
  
  <p>EDIT: I've tried different variations of removing the mappedBy-parameter and defining a JoinTable (and columns), but I've been unable to find the correct combination.</p>