Bug 124620 Referenced Parameter icon should be invalid if the parameter in library is deleted
Description: Referenced parameter icon should be invalid if the source parameter in library is deleted. Steps to reproduce: 1.Create a library. Insert a report scalar parameter. 2.Create a report, use the above library. In the library explorer, pull the parameter to the data explorer view of report. 3.Open the library file, delete the parameter. Then reopen the report design file, the icon of parameter seems nothing happened. But if those operations happened in dataset, the icon of dataset in the report will be invalid. It is acceptable. Expected Result: The icon of referenced parameter should be invalid.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/core/DesignElement.java
}
	/**
	 * Caches the child-to-container relationship. The caller must have
	 * validated that the relationship is valid.
	 * <p>
	 * Part of: The containment system.
	 * 
	 * @param obj
	 *            the container to set
	 * @param slot
	 *            the slot within the container where this element resides
	 */
	public void setContainer( DesignElement obj, int slot )
	{
		container = obj;
		containerSlotID = slot;
	}
	/**
	 * Gets the property data for either a system-defined or user-defined
	 * property.
	 * <p>
	 * Part of: Property system and user-defined property system
	 * 
	 * @param propName
	 *            The name of the property to lookup.
	 * @return The property definition, or null, if the property is undefined.
	 */
	public ElementPropertyDefn getPropertyDefn( String propName )
	{