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
* "extended" type.
 * <p>
 * User-defined inheritance is limited to elements of the same type. A label can
 * extend another label, but it cannot extend a data element, say.
 * <p>
 * System inheritance is used to define properties in a base class that should
 * be inherited by derived classes. User-inheritance implicitly inherits
 * properties, but focuses on inheriting property values. That is, user
 * inheritance allows Label B to inherit a font color of red from Label A. As
 * noted above, elements can define user properties. These property definitions
 * also are inherited with user inheritance. that is, if Label A defines a new
 * "Blink Rate" property, then label B (which extends label A) also has this
 * property.
 * 
 * <h3>Styles</h3>
 * 
 * BIRT includes the idea of styles. A style is simply a set of visual
 * information defined once in a design but used by many elements. At the core
 * level that we are discussing here, styles introduce a couple of interesting
 * twists to the design of the meta-data and element systems.
 * <p>
 * First some element types are defined to "have" a style. Having a style means
 * two things. First, the user can specify the name of a shared style to
 * associate with the element. Second, means that the element logically has a
 * "private style" that includes all the style properties relevant to that
 * element. In practice, any element type that has a style treats style
 * properties as though they were actual properties of the element type itself.
 * <p>
 * The meta-data file defines the style element, and this definition includes a
 * set of properties. Most of these represent properties that are to be applied