GTFS Flex V1 Support of Null stop_id in stop_time if there is a service area provided #17

[mmaranda-cs]

Summary:

GTFS FLex V1 not fully supported because stop_id is required in stop_time

Steps to reproduce:

How can we reproduce the issue? modify a stop_times file to have a null stop_id in an entry and a valid start_service_area

Expected behavior:
Per the GTFS Flex Spec a, technically, correct interpretation is that the stop_id in stop_times.txt can be null if there is a start or end service area provided. Although most agencies have followed the suggestion to include a phantom stop in the middle of the service area proper adherence to the spec does not require it.

To support that I propose making the stop_id optional. Then after reading in the GTFS validate that all provided stop_times have a stop_id unless the entry includes a start or end service_area.

Observed behavior:

GTFS Modules throws an error because the stop_id is required

[mmaranda-cs]

Fixed an error in the title