question: public void discard ( ServiceRegistrar reg ) { synchronized ( registrars ) { if ( terminated ) { throw new IllegalStateException ( "discovery terminated" ) ; } if ( reg == null ) return ; sendDiscarded ( reg , null ) ; } }
target:  Discard a registrar from the set of registrars already discovered.  This does not prevent that registrar from being rediscovered; it is intended to be used to clear unreachable entries from the set. <p> If the registrar has been discovered using this LookupDiscovery object, each listener registered with this object will have its discarded method called with the given registrar as parameter.