final BlobTransferStatus transferStatus = blobTransferTarget.getActiveTransfer(request.transferId);
assert transferStatus != null :
"Received GetBlobHeadRequest for transfer " + request.transferId.toString() + " but don't have an activeTransfer with that id";
BlobTransferInfoResponse response = new BlobTransferInfoResponse(
transferStatus.index(),
transferStatus.digestBlob().getDigest()
);
channel.sendResponse(response);
}