docs: public HashMap<KafkaTopicPartition, Long> snapshotCurrentState() {
  		// this method assumes that the checkpoint lock is held
  		assert Thread.holdsLock(checkpointLock);
  
  		HashMap<KafkaTopicPartition, Long> state = new HashMap<>(subscribedPartitionStates.size());
  		for (KafkaTopicPartitionState<KPH> partition : subscribedPartitionStates) {
  			state.put(partition.getKafkaTopicPartition(), partition.getOffset());
  		}
  		return state;
  	}