GroupElement.GROUP_NAME_PROP );
IGroupElementModel.GROUP_NAME_PROP );
	protected List checkContent( Module module, DesignElement container,			int slotId, DesignElement content )	{		List errors = super.checkContent( module, container, slotId, content );		if ( !errors.isEmpty( ) )			return errors;		// do the check of the group name		if ( content instanceof GroupElement )		{			String checkedName = (String) content.getLocalProperty( module,					GroupElement.GROUP_NAME_PROP );			if ( StringUtil.isBlank( checkedName ) )				return errors;			errors.addAll( GroupNameValidator.getInstance( )					.validateForAddingGroup(							(ListingHandle) getHandle( module ), checkedName ) );		}		return errors;	}