@Override
  protected ServerErrorCode validateRequest(PartitionId partition, RequestOrResponseType requestType,
      boolean skipPartitionAvailableCheck) {
    // 1. Check partition is null
    if (partition == null) {
      metrics.badRequestError.inc();
      return ServerErrorCode.BadRequest;
    }
    return ServerErrorCode.NoError;
  }
Request implementation class for Vcr. All requests to the vcr server are
handled by this class.
ambry-vcr/src/main/java/com/github/ambry/vcr/VcrRequests.java