title: removeif() not working on list returned by jpa
body: <p>I've some problem understanding why I can't use removeIf() on a collection returned by jpa but I can use an iterator to do so. </p>
  
  <pre><code>@PersistenceContext(unitName = "my-pu")
  private EntityManager em;
  @Override
  public void removeUserFromGroup(String username, Group group) {
      Query query = em.createNamedQuery("Group.getByName", Group.class);
      query.setParameter("name", group.getGroupName());
      Group qGroup = (Group) query.getSingleResult();
      // this works
      // Iterator&lt;User&gt; i = qGroup.getUsers().iterator();
      // while (i.hasNext()) {
      // User o = i.next();
      // if (o.getUsername().equals(username)) {
      // System.out.println("eqqq");
      // i.remove();
      // }
      // }
      System.out.println("class: " + qGroup.getUsers().getClass().getName());
      // org.eclipse.persistence.indirection.IndirectList
      qGroup.getUsers().removeIf(u -&gt; u.getUsername().equals(username));// doesn't work
  }
  </code></pre>