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/api/metadata/PropertyValueException.java
* element, and the value of the property cannot be set in a derived
	 * element.
	 */
	public static final String DESIGN_EXCEPTION_VALUE_LOCKED = MessageConstants.PROPERTY_VALUE_EXCEPTION_VALUE_LOCKED;
	/**
	 * Error code constant indicating unit is not allowed for the dimension
	 * property.
	 */
	public static final String DESIGN_EXCEPTION_UNIT_NOT_ALLOWED = MessageConstants.PROPERTY_VALUE_EXCEPTION_UNIT_NOT_ALLOWED;
	/**
	 * Error code constant indicating the choice value is not allowed for a
	 * choice type property.
	 */
	public static final String DESIGN_EXCEPTION_CHOICE_NOT_ALLOWED = MessageConstants.PROPERTY_VALUE_EXCEPTION_CHOICE_NOT_ALLOWED;
	/**
	 * The extension property of ExtendedItem is forbidden to be set by
	 * commands.
	 */
	public static final String DESIGN_EXCEPTION_EXTENSION_SETTING_FORBIDDEN = MessageConstants.PROPERTY_VALUE_EXTENSION_SETTING_FORBIDDEN;
	/**
	 * Within child element, properties that can cause structure change are not
	 * allowed to set.
	 */
	public static final String DESIGN_EXCEPTION_PROPERTY_CHANGE_FORBIDDEN = MessageConstants.PROPERTY_VALUE_EXCEPTION_PROPERTY_CHANGE_FORBIDDEN;
	/**
	 * The character "." is forbidden to NamePropertyType.
	 */
	public static final String DESIGN_EXCEPTION_DOT_FORBIDDEN = MessageConstants.PROPERTY_VALUE_EXCEPTION_DOT_FORBIDDEN;
	/**
	 * Constructs an exception given an invalid value, error code and the