GTFS Flex spec update: separate columns for location_id, location_group_id

[leonardehrenfried]

Summary

At the latest GTFS Flex working group we decided that we want to put location_id and location_group_id into their separate columns in order to make it clearer what is a flex trip and what isn't.

This PR catches up with this spec change and uses some Java 21 features to clean up the code a little.

Lastly, since the stop_id column can now be empty, I added

Unit tests

✔️

cc @westontrillium @tzujenchanmbd @tsherlockcraig @eliasmbd @gcamp

[codecov]

Codecov Report

Attention: 8 lines in your changes are missing coverage. Please review.

Comparison is base (4230fd3) 67.35% compared to head (40fcc74) 67.38%.
Report is 1 commits behind head on dev-2.x.

❗ Current head 40fcc74 differs from pull request most recent head cbad217. Consider uploading reports for the commit cbad217 to get more accurate results

Files	Patch %	Lines
...ntripplanner/gtfs/mapping/LocationGroupMapper.java	28.57%	4 Missing and 1 partial ⚠️
...g/opentripplanner/gtfs/mapping/StopTimeMapper.java	66.66%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@              Coverage Diff              @@
##             dev-2.x    #5564      +/-   ##
=============================================
+ Coverage      67.35%   67.38%   +0.02%     
- Complexity     16162    16169       +7     
=============================================
  Files           1858     1858              
  Lines          71093    71095       +2     
  Branches        7403     7399       -4     
=============================================
+ Hits           47888    47904      +16     
+ Misses         20745    20732      -13     
+ Partials        2460     2459       -1     

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[vpaturet]

I need a bit of context regarding the changes in onebusaway-gtfs/src/main/java/org/onebusaway/gtfs/model/StopTime.java, notably the difference between the getters getStop(), getLocation(), .. that go through StopTimeProxy and getStopLocation() that does not go through that proxy.

[vpaturet]

location.getClass() triggers a NullPointerException if location == null
Is "case null" actually a possible code path?

[leonardehrenfried]

I've cleaned this up here:
8c3411c

I made the null check more explicit and added a nicer error message.

[leonardehrenfried]

I need a bit of context regarding the changes in onebusaway-gtfs/src/main/java/org/onebusaway/gtfs/model/StopTime.java, notably the difference between the getters getStop(), getLocation(), .. that go through StopTimeProxy and getStopLocation() that does not go through that proxy.

I'm not really sure what the proxy is used for but it only exists for getters for which there is a proper column in GTFS. The getStopLocation on the other hand is just a convenience method that goes through the stop, location or location group columns to find the first non-empty one (previously you used stop_id also for flex stops). Since it doesn't have a corresponding column, it doesn't have a proxy.