question: public Set registerClientInterestList ( Object inputClientID , List keys , boolean updatesAsInvalidates ) { Long clientID = getClientIDForMaps ( inputClientID ) ; Set keysRegistered = new HashSet ( keys ) ; synchronized ( interestListLock ) { Map < Object , Set > koi = updatesAsInvalidates ? getKeysOfInterestInv ( ) : getKeysOfInterest ( ) ; CopyOnWriteHashSet interestList = ( CopyOnWriteHashSet ) koi . get ( clientID ) ; if ( interestList == null ) { interestList = new CopyOnWriteHashSet ( ) ; koi . put ( clientID , interestList ) ; } else { keysRegistered . removeAll ( interestList . getSnapshot ( ) ) ; } interestList . addAll ( keys ) ; if ( this . region != null && this . isLocalProfile ) { sendProfileOperation ( clientID , operationType . REGISTER_KEYS , keys , updatesAsInvalidates ) ; } } return keysRegistered ; }
target:  Registers interest in a set of keys for a client