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/PropertySearchStrategy.java
* gets the "effective" property value. The definition can be for a system
	 * or user-defined property.
	 * <p>
	 * The search won't search up the containment hierarchy. Meanwhile, it won't
	 * the inheritance hierarchy if the non-style property is not inheritable.
	 * <p>
	 * Part of: Property value system.
	 * 
	 * @param module
	 *            the module
	 * @param element
	 *            the element to search
	 * @param prop
	 *            definition of the property to get
	 * @return The property value, or null if no value is set.
	 */
	public Object getPropertyFromElement( Module module, DesignElement element,
			ElementPropertyDefn prop )
	{
		Object value = null;
		value = getPropertyFromSelf( module, element, prop );
		if ( value != null )
			return value;
		
		
		
		if ( isInheritableProperty( element, prop ) || prop.isStyleProperty( ) )
		{
			value = getPropertyFromParent( element, prop );
			if ( value != null )