private void registerKeyInMap(Object interest, Set keysRegistered, Long clientID,
      Map<Object, Set> koi) {
    Set interestList = koi.get(clientID);
    if (interestList == null) {
      interestList = new CopyOnWriteHashSet();
      koi.put(clientID, interestList);
    }
    interestList.add(interest);
    keysRegistered.add(interest);
  }
Registers interest in the input region name and key

@param inputClientID The identity of the interested client
@param interest The key in which to register interest
@param typeOfInterest the type of interest the client is registering
@param updatesAsInvalidates whether the client just wants invalidations
@return a set of the keys that were registered, which may be null
geode-core/src/main/java/org/apache/geode/internal/cache/FilterProfile.java