Bug 138562 Splite extendsexcpetion to seperate sub class
The suggestion is Parent invalid Cycle extends Different type extends Not top level extends
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/core/DesignElement.java
* sent for each change using subclasses of the {@link NotificationEvent}class.
 * See these two classes for more details.
 * <p>
 * Note: subscribing and unsubscribing listeners is the only mutator operation
 * that the application can (and should) do without the use of a command.
 * <p>
 * Members and classes in the notification system include:
 * <p>
 * <ul>
 * <li>The {@link #listeners}member holds the list of subscribed listeners.
 * </li>
 * <li>The {@link #addListener}and {@link #removeListener}methods to add and
 * remove listeners.</li>
 * <li>The {@link Listener}class to receive notifications.</li>
 * <li>A subclass of {@link NotificationEvent}notifies the listener of the
 * type of change, and information about the change.</li>
 * <li>The {@link org.eclipse.birt.report.model.activity.ActivityStack}class
 * triggers the notifications as it processes commands.</li>
 * <li>ActivityStack calls the {@link #sendEvent}method to send the
 * notification to the appropriate listeners.</li>
 * <li>The sendEvent( ) method in turn calls
 * {@link #broadcast(NotificationEvent)}to do the detailed work of sending an
 * event to all the listeners.</li>
 * </ul>
 * 
 * <h3>Element Identity</h3>
 * 
 * There are four ways to refer to an item:
 * <p>
 * <dl>