Bug 119550 Default Value of Named Expression can't be saved in design file
New a report, set named expression in the report property editor add a named expression and set the default value add a report item, say table, to the layout set the named expression of the report item add a named expression and set hte default value save the report close the report and reopen, and there is no default named expression value displayed. open report design file with a text editor, there is no default value associate with the named expression
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/core/UserPropertyDefn.java
* 
	 */
	public String getDisplayName( )
	{
		
		if ( !StringUtil.isBlank( displayName ) )
		{
			
			return displayName;
		}
		
		return name;
	}
	/**
	 * Sets the display name of the property. Use this only for testing; you
	 * should normally set the display name message ID so that the name can be
	 * retrieved from a message catalog and localized.
	 * 
	 * @param theName
	 *            the display name to set
	 */
	public void setDisplayName( String theName )
	{
		displayName = theName;
	}
	/**
	 * Sets the (anonymous) set of choices for a property. The choices are
	 * stored here directly, they are not named and stored in the data
	 * dictionary as are choices for system properties.
	 *