Support for Trip matching when only Route is specified in transfers.txt #3429
Description
The Trip-To-Trip GFTS Transfers Google extension.
The Google transfers extension allow a transfers to be specified for a stop in combination with a route or trip. With PR #3427 OTP support (stop, trip), but not (stop, route).
To implement support for (stop, route), the transfer need to be applied at a (stop, trip) level using static/planned data. The simplest way to do this is to expand (stop, route) for all trips part of route. Doing this at runtime during a travel search would require both static data and real-time data to be considered and is most likely to be slow.