@Override
  public String toString() {
    StringBuilder sb = new StringBuilder();
    sb.append(", ").append("PartitionId=").append(partitionId);
    sb.append("ListOfBlobIDs=").append(blobIds);
    return sb.toString();
  }
Contains the partition and the blob ids requested from a partition. This is used
by get request to specify the blob ids in a partition
ambry-protocol/src/main/java/com/github/ambry/protocol/PartitionRequestInfo.java