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
child.gatherDescendents( list );
		}
	}
	/**
	 * Checks if the element has defined any user properties. Checks only this
	 * element, not its parents.
	 * 
	 * @return True if the element has user properties, false if not.
	 */
	public boolean hasUserProperties( )
	{
		return userProperties != null && !userProperties.isEmpty( );
	}
	/**
	 * Checks if this element has any locally-defined property values.
	 * 
	 * @return True if the element has property values, false if not.
	 */
	public boolean hasLocalPropertyValues( )
	{
		return !propValues.isEmpty( );
	}
	/**
	 * Returns the container interface for this element if this element is a
	 * container. Derived classes that represent containers must override this.
	 * <p>
	 * Part of: Containment system.
	 * 
	 * @param slot
	 *            the slot ID to get