@Override
  public String toString() {
    StringBuilder sb = new StringBuilder();
    sb.append("PartitionResponseInfo[");
    sb.append("PartitionId=").append(partitionId);
    sb.append(" ServerErrorCode=").append(errorCode);
    sb.append(" MessageInfoAndMetadataListSize=").append(messageInfoAndMetadataListSize);
    sb.append("]");
    return sb.toString();
  }
Contains the partition and the message info list for a partition. This is used by
get response to specify the message info list in a partition
ambry-protocol/src/main/java/com/github/ambry/protocol/PartitionResponseInfo.java