public boolean hasNewMessages(SystemStreamPartitionIterator iterator) {
    if (iterator == null) {
      return false;
    }
    return iterator.hasNext();
  }
Checks whether or not there are any messages after a given iterator on the coordinator stream

@param iterator The iterator to check if there are any new messages after this point
@return True if there are new messages after the iterator, false otherwise
samza-core/src/main/java/org/apache/samza/coordinator/stream/CoordinatorStreamSystemConsumer.java