question: protected boolean updateAttachmentPoint ( ) { boolean moved = false ; this . oldAPs = attachmentPoints ; if ( attachmentPoints == null || attachmentPoints . isEmpty ( ) ) return false ; List < AttachmentPoint > apList = new ArrayList < AttachmentPoint > ( ) ; if ( attachmentPoints != null ) apList . addAll ( attachmentPoints ) ; Map < Long , AttachmentPoint > newMap = getAPMap ( apList ) ; if ( newMap == null || newMap . size ( ) != apList . size ( ) ) { moved = true ; } if ( moved ) { log . info ( "updateAttachmentPoint: ap {}  newmap {} " , attachmentPoints , newMap ) ; List < AttachmentPoint > newAPList = new ArrayList < AttachmentPoint > ( ) ; if ( newMap != null ) newAPList . addAll ( newMap . values ( ) ) ; this . attachmentPoints = newAPList ; } return moved ; }
target:  Update the known attachment points.  This method is called whenever topology changes. The method returns true if there's any change to the list of attachment points -- which indicates a possible device move.