repeated .transit_realtime.TripUpdate.StopTimeUpdate stop_time_update = 2;
Updates to StopTimes for the trip (both future, i.e., predictions, and in
some cases, past ones, i.e., those that already happened).
The updates must be sorted by stop_sequence, and apply for all the
following stops of the trip up to the next specified one.
Example 1:
For a trip with 20 stops, a StopTimeUpdate with arrival delay and departure
delay of 0 for stop_sequence of the current stop means that the trip is
exactly on time.
Example 2:
For the same trip instance, 3 StopTimeUpdates are provided:
- delay of 5 min for stop_sequence 3
- delay of 1 min for stop_sequence 8
- delay of unspecified duration for stop_sequence 10
This will be interpreted as:
- stop_sequences 3,4,5,6,7 have delay of 5 min.
- stop_sequences 8,9 have delay of 1 min.
- stop_sequences 10,... have unknown delay.