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
* reference is just a name, but the system has not yet identified the
	 * target element, or if a target even exists. A resolved reference caches a
	 * pointer to the target element itself.
	 * 
	 * @param oldRef
	 *            the old reference, if any
	 * @param newRef
	 *            the new reference, if any
	 * @param prop
	 *            definition of the property
	 */
	protected void updateReference( ElementRefValue oldRef,
			ElementRefValue newRef, ElementPropertyDefn prop )
	{
		ReferenceableElement target;
		
		
		if ( oldRef != null )
		{
			target = oldRef.getTargetElement( );
			if ( target != null )
				target.dropClient( this );
		}
		
		
		
		if ( newRef != null )
		{
			target = newRef.getTargetElement( );
			if ( target != null )