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 search won't search up the inheritance hierarchy if the property is
	 * defined to not inherit.
	 * <p>
	 * Part of: Property value system.
	 * 
	 * @param module
	 *            the module
	 * @param propName
	 *            name of the property to get. Can be a system-defined or
	 *            user-defined property name. Must be of the correct case.
	 * @return The property value, or null if no value is set.
	 */
	public Object getProperty( Module module, String propName )
	{
		ElementPropertyDefn prop = getPropertyDefn( propName );
		
		if ( prop == null )
			return null;
		return getProperty( module, prop );
	}
	/**
	 * Gets a property value given its definition. This version does the full
	 * property search as defined by the given derived component. That is, it
	 * gets the "effective" property value. The definition can be for a system
	 * or user-defined property.
	 * <p>
	 * The search won't search up the inheritance hierarchy if the non-style
	 * property is defined to not inherit. And style property won't be searched
	 * up the containment hierarchy if it'd defined to no inherit.
	 * <p>