Bug 124620 Referenced Parameter icon should be invalid if the parameter in library is deleted
Description: Referenced parameter icon should be invalid if the source parameter in library is deleted. Steps to reproduce: 1.Create a library. Insert a report scalar parameter. 2.Create a report, use the above library. In the library explorer, pull the parameter to the data explorer view of report. 3.Open the library file, delete the parameter. Then reopen the report design file, the icon of parameter seems nothing happened. But if those operations happened in dataset, the icon of dataset in the report will be invalid. It is acceptable. Expected Result: The icon of referenced parameter should be invalid.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/core/DesignElement.java
* defined in a subclass of this class.
 * <p>
 * However, all content elements have at most one container. And, all elements
 * (except the root) have a container. So, the content-to-container relationship
 * is modelled in this element base class.
 * <p>
 * Containers have one or more <em>slots </em>. See the
 * {@link org.eclipse.birt.report.model.metadata.SlotDefn}class for a detailed
 * description of slots.
 * <p>
 * Members in the containment system include:
 * <p>
 * <ul>
 * <li>The {@link #container}member that caches a pointer to the container
 * element.</li>
 * <li>The {@link #getContainer}method to get the container element.</li>
 * <li>The {@link #setContainer}method to set the container element.</li>
 * <li>The {@link #getSlot}method returns a slot within a container.
 * <li>The {@link ContainerSlot},{@link SingleElementSlot}and
 * {@link MultiElementSlot}classes that represent slots.</li>
 * </ul>
 * 
 * <h3>Change Notification</h3>
 * 
 * Any given element may be "visualized" in multiple places in the user
 * interface. If the user changes the element, all the affected parts of the UI
 * must be updated. The notification system is responsible for these updates.
 * <p>
 * The notification system allows any number of {@link Listener}objects to
 * subscribe to receive change notifications for an element. Notifications are