question: public boolean deleteAttachmentPoint ( DatapathId sw , OFPort port ) { AttachmentPoint ap = new AttachmentPoint ( sw , port , new Date ( 0 ) ) ; if ( this . oldAPs != null ) { ArrayList < AttachmentPoint > apList = new ArrayList < AttachmentPoint > ( ) ; apList . addAll ( this . oldAPs ) ; int index = apList . indexOf ( ap ) ; if ( index > 0 ) { apList . remove ( index ) ; this . oldAPs = apList ; } } if ( this . attachmentPoints != null ) { ArrayList < AttachmentPoint > apList = new ArrayList < AttachmentPoint > ( ) ; apList . addAll ( this . attachmentPoints ) ; int index = apList . indexOf ( ap ) ; if ( index > 0 ) { apList . remove ( index ) ; this . attachmentPoints = apList ; return true ; } } return false ; }
target:  Delete (sw,port) from the list of list of attachment points and oldAPs.