public Set<InterestRegistrationListener> getInterestRegistrationListeners() {
    return readableInterestRegistrationListeners;
  }
Returns a read-only collection of {@code InterestRegistrationListener}s registered with
this notifier.

@return a read-only collection of {@code InterestRegistrationListener}s registered with
        this notifier

@since GemFire 5.8Beta
geode-core/src/main/java/org/apache/geode/internal/cache/tier/sockets/CacheClientNotifier.java