Bug 197228 Need updaet createdBy info when serialize the module
When open module, designer will pass the property map which contains the createdBy info. this info should be retained by moduleHandle and then be updated and written when doing serialization. Note if this info is null, model should not update it during serialization. This could happen for api users or third-party designer. For BIRT designer, it will guarantee this value always not null.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/core/Module.java
return validationListeners.remove( listener );
	}
	/**
	 * Broadcasts the validation event to validation listeners.
	 * 
	 * @param element
	 *            the validated element
	 * @param event
	 *            the validation event
	 */
	public void broadcastValidationEvent( DesignElement element,
			ValidationEvent event )
	{
		if ( validationListeners != null )
		{
			Iterator iter = validationListeners.iterator( );
			while ( iter.hasNext( ) )
			{
				IValidationListener listener = (IValidationListener) iter
						.next( );
				listener.elementValidated( element.getHandle( this ), event );
			}
		}
	}
	/**
	 * Makes a unique name for an element. There are several cases.
	 * <p>
	 * <dl>
	 * <dt>Blank name, name is optional</dt>
	 * <dd>Leave the name blank, for some elements the name is optional.</dd>