@Override
  public String toString() {
    return "CheckpointV2 [CHECKPOINT_VERSION=" + CHECKPOINT_VERSION + ", checkpointId=" + checkpointId +
        ", inputOffsets=" + inputOffsets + ", stateCheckpointMarkers=" + stateCheckpointMarkers + "]";
  }
Gets the state checkpoint markers for all stores for each configured state backend.

Note: We don't add this method to the {@link Checkpoint} interface since it is difficult
to implement it for {@link CheckpointV1} without changing the underlying serialization format -
the changelog SSP offsets are serialized in the same way as input offsets, and at
deserialization time we don't have enough information (e.g. configs) to decide whether a
particular entry is for an input SSP or a changelog SSP.

@return Map of state backend factory name to map of local state store names to state checkpoint markers
samza-api/src/main/java/org/apache/samza/checkpoint/CheckpointV2.java