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
return false;
		PropertyType type = MetaDataDictionary.getInstance( ).getPropertyType(
				prop.getTypeCode( ) );
		Object value = getProperty( module, propName );
		return ( (BooleanPropertyType) type ).toBoolean( module, value );
	}
	/**
	 * Gets the value of a property as a list.
	 * 
	 * @param module
	 *            the module
	 * @param propName
	 *            the name of the property to get
	 * @return the value as an <code>ArrayList</code>, or null if the
	 *         property is not set or the value is not a list
	 */
	public List getListProperty( Module module, String propName )
	{
		Object value = getProperty( module, propName );
		if ( value == null )
			return null;
		if ( value instanceof ArrayList )
			return (ArrayList) value;
		return null;
	}
	/**
	 * Gets the set of property definitions available to this element. Includes
	 * all properties defined for this element, all user-defined properties
	 * defined on this element or its ancestors, and any style properties that
	 * this element supports.