Bug 149251 Inconsistent Handling of a Non-inheritable ROM Property
For a ROM property defined to be non-inheritable, an empty string property value should be consistently handled as an empty string, not as null. For example, an oda.dataSource extension defines a data source property with canInherit=false. When a oda-data-source handle get saved in a report design, it correctly includes the tag for such property, even when an empty string value is specified. <oda-data-source extensionID="my.oda.plugin" name="my Data Source" id="24"> ... <property name="ApplicationServer"></property> </oda-data-source> However, later when using the DE API to read its property value, a null is returned. Then when the report design is subsequently saved, the property tag is lost. Expects that an empty string value of a non-inhertiable property should be preserved.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/core/DesignElement.java
* Registers a listener. A listener can be registered any number of times,
	 * but will receive each event only once.
	 * <p>
	 * Part of: Notification system.
	 * 
	 * @param obj
	 *            the listener to register
	 */
	public void addListener( Listener obj )
	{
		if ( listeners == null )
			listeners = new ArrayList( );
		if ( obj != null && !listeners.contains( obj ) )
			listeners.add( obj );
	}
	/**
	 * Removes a listener. The listener is removed from the list of listeners.
	 * If the item is not in the list, then the request is silently ignored.
	 * <p>
	 * Part of: Notification system.
	 * 
	 * @param obj
	 *            the listener to remove
	 */
	public void removeListener( Listener obj )
	{
		if ( listeners == null )
			return;
		int posn = listeners.indexOf( obj );
		if ( posn != -1 )