instanceChanged();
instanceChanged($instance);
  public final void setInstance(final PersistentBean instance) throws IllegalArgumentException {    LOG.debug("setting instance to " + instance);    if ((instance != null) && (!getPersistentBeanType().isAssignableFrom(instance.getClass()))) {      throw new IllegalArgumentException("instance " + instance                                         + " is not a subtype of "                                         + getPersistentBeanType());    }    $instance = instance;    if (instance != null) {      setId(instance.getId());    }    else {      // else, we do NOT set the ID to null      LOG.debug("instance set to null; id is left untouched (" + getId() + ")");    }    instanceChanged();  }