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 slot id of the container element
	 * @param defn
	 *            the element definition
	 * @return a list containing exceptions.
	 */
	protected List checkContent( Module module, DesignElement container,
			int slotId, IElementDefn defn )
	{
		return new ArrayList( );
	}
	/**
	 * Returns the slot within the container element that holds this element.
	 * 
	 * @return the container's slot in which this element appears
	 */
	public int getContainerSlot( )
	{
		return containerSlotID;
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.report.model.core.IPropertySet#getObjectDefn()
	 */
	public IObjectDefn getObjectDefn( )
	{
		return getDefn( );
	}
	/**
	 * Returns the value of an element reference property as an element. Returns