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/metadata/ElementDefn.java
* The property is shown in the property sheet but readonly.
	 */
	protected final static String READONLY_IN_PROPERTY_SHEET = "readonly"; 
	/**
	 * Whether this definition represents an abstract element that the user
	 * normally does not see. Abstract elements exist to organize the element
	 * system.
	 */
	protected boolean abstractElement = false;
	/**
	 * The name of base element, if any, from which this element extends.
	 */
	protected String extendsFrom = null;
	/**
	 * The parent Element meta-data object (specified by the "extendsFrom"
	 * value).
	 */
	protected ElementDefn parent = null;
	/**
	 * specify if the element has a style.
	 */
	protected boolean hasStyle = false;
	/**
	 * Flag used when caching meta data.
	 */
	protected boolean isBuilt = false;
	/**
	 * The predefined style, if any, for this element. The style name is the
	 * internal name.
	 */