Bug 163018 An error extension will lead the report contain chart can't be opened and can not new a report.
Details: An error extension will lead the report contain chart can't open In org.eclipse.birt.report.tests.model has an error extension. When run the birt use workbenck, the report contain chart can't be opened and it can not new a report.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/metadata/ElementDefn.java
* 
 * <h3>Containment</h3>
 * 
 * <em>Container</em> elements contain <em>content</em> elements. Some
 * containers store just one set of contents, others store multiple sets. Each
 * set of contents is called a <em>slot</em>. Each slot has a cardinality
 * (one or many), and a type. More specifically, each slot can contain a set of
 * element types. The {@link SlotDefn}class holds details of a slot.
 * <p>
 * Slots are indexed using a slot ID. The ID is a zero-based index, allowing the
 * caller to easily iterate over the slots.
 * 
 * <h3>Names and Name Spaces</h3>
 * 
 * Elements can have a name. Some elements require a name, for some the name is
 * optional.
 * <p>
 * The element name is meant to be unique within a <em>name space</em>. Name
 * spaces reside on the root element. Name spaces include elements, styles, data
 * sources, data sets and so on. Each element type identifies its name space
 * using a name space ID.
 * 
 * <h3>Method</h3>
 * 
 * Elements can have methods that defines the script. All methods are defined in
 * metadata. The element can inherit the methods defined in parent. Property
 * mask can change the method visibility.
 */
public class ElementDefn extends ObjectDefn implements IElementDefn
{