An InboundTransferTask handles multiple segments, not just one. I added the word 'multiple' to the javadoc to make it clearer. All those segments are from the same source. There could be multiple InboundTransferTasks running at the same time, but a certain segment is handled by at most one such task. There could be 0 if the segment does not need fetching but never more than one. This PR is also changing the 'multiple InboundTransferTasks running at the same time'. There will be only one.