@Override
  public void accept(RequestVisitor visitor) {
    // TODO Efficient_Metadata_Operations_TODO: Implement this.
  }
@param correlationId the correlation id for the request
@param clientId the id of the client generating the request
@param blobId the blob ID that needs to be purged.
@param purgeTimeInMs purge time of the blob in ms
@param version the version of the {@link PurgeRequest}.
ambry-protocol/src/main/java/com/github/ambry/protocol/PurgeRequest.java