docs: @GuardedBy("maxNumberInvariant")
     private void resetNumberOfKeys() {
        maxNumberOfKeys.set(address2key.keySet().size() * bufferSize);
        existingKeyCount.set(0);
        if (trace) {
           log.tracef("resetNumberOfKeys ends with: maxNumberOfKeys=%s, existingKeyCount=%s",
                      maxNumberOfKeys.get(), existingKeyCount.get());
        }
     }