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
*            the value list to check
	 * @param toAdd
	 *            the value item to add. This parameter maybe is
	 *            <code>null</code>.
	 * @throws PropertyValueException
	 *             if the structure list or the item to add has any semantic
	 *             error..
	 */
	public void checkSimpleList( Module module, PropertyDefn propDefn,
			List list, Object toAdd ) throws PropertyValueException
	{
		List errorList = SimpleListValidator.getInstance( ).validateForAdding(
				getHandle( module ), propDefn, list, toAdd );
		if ( errorList.size( ) > 0 )
		{
			throw (PropertyValueException) errorList.get( 0 );
		}
	}
	/**
	 * The common logic for both clone and cloneForTemplate.
	 * 
	 * @return the clone element with reference to parent in library
	 * @throws CloneNotSupportedException
	 */
	final private Object baseClone( ) throws CloneNotSupportedException
	{
		DesignElement element = (DesignElement) super.clone( );
		element.container = null;
		element.listeners = null;
		element.derived = null;